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Here are some of the more frequently asked questions about using
Linux with an Ethernet connection. Some of the more specific
questions are sorted on a `per manufacturer basis'.
Chances are the question you want an answer for has already
been asked (and answered!) by someone else, so even if you
don't find your answer here, you probably can find what you
want from a news archive such as
Dejanews.
The answer to this question depends heavily on exactly what
you intend on doing with your net connection, and how much
traffic it will see.
If you only expect a single user to be doing the occasional
ftp session or WWW connection, then even an old 8 bit ISA card
will probably keep you happy.
If you intend to set up a server, and you require the CPU
overhead of moving data over the network to be kept
to a minimum, you probably want to look at one of the
PCI cards that uses a chip with bus-mastering capapbility,
such as the DEC tulip (21xxx) chip, or the AMD PCnet-PCI chip.
If you fall somewhere in the middle of the above, then any
one of the low cost PCI or 16 bit ISA cards with stable
drivers will do the job for you.
I heard that there is an updated or preliminary/alpha driver
available for my card. Where can I get it?
The newest of the `new' drivers can be found on Donald's
ftp site: www.scyld.com in the
/pub/linux/ area. Things
change here quite frequently, so just look around for it.
Alternatively, it may be easier to use a WWW browser on:
Don's Linux Home Page to locate the driver that you are looking for. (Watch out for
WWW browsers that silently munge the source by replacing
TABs with spaces and so on - use ftp, or at least an FTP URL
for downloading if unsure.)
Now, if it really is an alpha, or pre-alpha driver, then please
treat it as such. In other words, don't complain because you
can't figure out what to do with it. If you can't figure out
how to install it, then you probably shouldn't be testing it.
Also, if it brings your machine down, don't complain. Instead,
send us a well documented bug report, or even better, a patch!
Note that some of the `useable' experimental/alpha drivers have
been included in the standard kernel source tree. When running
make config one of the first things you will be asked
is whether to ``Prompt for development and/or incomplete
code/drivers''. You will have to answer `Y' here to get
asked about including any alpha/experiemntal drivers.
What needs to be done so that Linux can run two ethernet cards?
The answer to this question depends on whether the driver(s)
is/are being used as a loadable module or are compiled directly
into the kernel. Most linux distributions use modular drivers now.
This saves distributing lots of kernels, each with a different driver
set built in. Instead a single basic kernel is used and the
individual drivers that are need for a particular user's system are
loaded once the system has booted far enough to access
the driver module files (usually stored in /lib/modules/).
With the Driver as a Module:
In the case of
PCI drivers, the module will typically detect all of the
installed cards of that brand model automatically. However,
for ISA cards, probing for a card is not a safe operation, and
hence you typically need to supply the I/O base address of the
card so the module knows where to look. This information is
stored in the file /etc/conf.modules.
As an example, consider a user that has two ISA NE2000 cards,
one at 0x300 and one at 0x240 and what lines they
would have in their /etc/conf.modules file:
alias eth0 ne
alias eth1 ne
options ne io=0x240,0x300
What this does: This says that if the administrator (or the
kernel) does a modprobe eth0 or a modprobe eth1 then
the ne.o driver should be loaded for either eth0 or
eth1. Furthermore, when the ne.o module is loaded, it
should be loaded with the options io=0x240,0x300 so that the
driver knows where to look for the cards. Note that the 0x
is important - things like 300h as commonly used in the DOS
world won't work. Switching the order of the 0x240 and
the 0x300 will switch which physical card ends up as
eth0 and eth1.
Most of the ISA module drivers can take multiple comma separated
I/O values like this example to handle multiple cards. However,
some (older?) drivers, such as the 3c501.o module are currently
only able to handle
one card per module load. In this case you can load the module
twice to get both cards detected. The /etc/conf.modules
file in this case would look like:
alias eth0 3c501
alias eth1 3c501
options eth0 -o 3c501-0 io=0x280 irq=5
options eth1 -o 3c501-1 io=0x300 irq=7
In this example the -o option has been used to give each
instance of the module a unique name, since you can't have two
modules loaded with the same name. The irq= option has
also been used to to specify the hardware IRQ setting of the card.
(This method can also be used with modules that accept comma
separated I/O values, but it is less efficient since the module
ends up being loaded twice when it doesn't really need to be.)
As a final example, consider a user with one 3c503 card
at 0x350 and one SMC Elite16 (wd8013) card at 0x280.
They would have:
alias eth0 wd
alias eth1 3c503
options wd io=0x280
options 3c503 io=0x350
For PCI cards, you typically only need the alias lines to
correlate the ethN interfaces with the appropriate driver
name, since the I/O base of a PCI card can be safely detected.
The available modules are typically stored in
/lib/modules/`uname -r`/net where the
uname -r command gives the kernel version (e.g. 2.0.34).
You can look in there to see which one matches your card.
Once you have the correct settings in your conf.modules
file, you can test things out with:
modprobe ethN
dmesg | tail
where `N' is the number of the ethernet interface you are testing.
With the Driver Compiled into the Kernel:
If you have the driver compiled into the kernel, then
the hooks for multiple ethercards are all there.
However, note that at the moment only one ethercard is
auto-probed for by default. This helps to avoid possible
boot time hangs caused by probing sensitive cards.
(Note: As of late 2.1.x kernels, the boot probes have been
sorted into safe and unsafe, so that all safe (e.g. PCI and
EISA) probes will find all related cards automatically. Systems
with more than one ethernet card with at least one of them
being an ISA card will still need to do one of the following.)
There are two ways that you can enable auto-probing for
the second (and third, and...) card. The easiest
method is to pass boot-time arguments to the kernel,
which is usually done by LILO. Probing for the
second card can be achieved by using a boot-time argument
as simple as ether=0,0,eth1. In this
case eth0 and eth1 will be assigned in the order
that the cards are found at boot. Say if you want
the card at 0x300 to be eth0 and
the card at 0x280 to be eth1 then you could use
LILO: linux ether=5,0x300,eth0 ether=15,0x280,eth1
The ether= command accepts more than the IRQ + I/O
+ name shown above. Please have a look at
Passing Ethernet Arguments...
for the full syntax, card specific parameters, and LILO tips.
These boot time arguments can be made permanent so that you
don't have to re-enter them every time. See the LILO
configuration option `append' in the LILO manual.
The second way (not recommended) is to edit the file
Space.c and replace the 0xffe0 entry for the
I/O address with a zero. The 0xffe0 entry tells it
not to probe for that device -- replacing it with a zero
will enable autoprobing for that device.
As described above, the ether= command only works
for drivers that are compiled into the kernel. Now most
distributions use the drivers in a modular form, and so
the ether= command is rarely used anymore. (Some older
documentation has yet to be updated to reflect this change.)
If you want to apply options for a modular ethernet driver
you must make changes to the /etc/conf.modules
file.
If you are using a compiled in driver, and have added
an ether= to your LILO configuration file, note
that it won't take effect until you re-run lilo
to process the updated configuration file.
Problem:
PCI NE2000 clone card is not detected at boot with v2.0.x.
Reason:
The ne.c driver up to v2.0.30 only knows about the PCI
ID number of RealTek 8029 based clone cards. Since then,
several others have also released PCI NE2000 clone
cards, with different PCI ID numbers, and hence the
driver doesn't detect them.
Solution:
The easiest solution is to upgrade to a v2.0.31 (or newer)
version of the
linux kernel. It knows the ID numbers of about five different
NE2000-PCI chips, and will detect them automatically at boot or
at module loading time. If you upgrade to 2.0.34 (or newer)
there is a PCI-only specific NE2000 driver that is slightly
smaller and more efficient than the original ISA/PCI driver.
Problem:
PCI NE2000 clone card is reported as an ne1000 (8 bit card!)
at boot or when I load the ne.o module for v2.0.x, and hence
doesn't work.
Reason:
Some PCI clones don't implement byte wide access (and hence are
not truly 100% NE2000 compatible). This causes the probe
to think they are NE1000 cards.
Solution:
You need to upgrade to v2.0.31 (or newer) as described above.
The driver(s) now check for this hardware bug.
Problem:
PCI NE2000 card gets terrible performance, even when reducing the
window size as described in the Performance Tips section.
Reason:
The spec sheets for the original 8390 chip, desgined and sold
over ten years ago, noted that a dummy read from the chip was
required before each write operation for maximum reliablity.
The driver has the facility to do this but it has been disabled
by default since the v1.2 kernel days. One user has reported that
re-enabling this `mis-feature' helped their performance with a
cheap PCI NE2000 clone card.
Solution:
Since it has only been reported as a solution by one person, don't
get your hopes up. Re-enabling the read before write fix is done
by simply editing the driver file in linux/drivers/net/,
uncommenting the line containing NE_RW_BUGFIX and then
rebuilding the kernel or module as appropriate. Please send an
e-mail describing the performance difference and type of card/chip
you have if this helps you. (The same can be done for the
ne2k-pci.c driver as well).
Problem:
The ne2k-pci.c driver reports error messages like
timeout waiting for Tx RDC with a PCI NE2000 card and doesn't
work right.
Reason:
Your card and/or the card to PCI bus link can't handle the long
word I/O optimization used in this driver.
Solution:
Firstly, check the settings available in the BIOS/CMOS setup
to see if any related to PCI bus timing are too aggressive for
reliable operation. Otherwise using the ISA/PCI ne.c
driver (or removing the #define USE_LONGIO from
ne2k-pci.c) should let you use the card.
Probem:
ISA Plug and Play NE2000 (such as RealTek 8019) is not detected.
Reason:
The original NE2000 specification (and hence the linux NE2000 driver)
does not have support for Plug and Play.
Solution:
Use the DOS configuration disk that came with the card to disable
PnP, and to set the card to a specified I/O address and IRQ. Add
a line to /etc/conf.modules like options ne io=0xNNN
where 0xNNN is the hex I/O address you set the card to. (This
assumes you are using a modular driver; if not then use an
ether=0,0xNNN,eth0 argument at boot). You may also have to
enter the BIOS/CMOS setup and mark the IRQ as Legacy-ISA instead of
PnP. Alternatively, if you
need to leave PnP enabled for compatibility with some other operating
system, then look into the isapnptools package. Try
man isapnp to see if it is already installed on your system.
If not, then have a look at the following URL:
ISA PNP Tools
Problem:
NE*000 driver reports `not found (no reset ack)' during boot
probe.
Reason:
This is related to the above change. After the initial
verification that an 8390 is at the probed I/O address, the
reset is performed. When the card has completed the reset,
it is supposed to acknowedge that the reset has completed.
Your card doesn't, and so the driver assumes that no NE card
is present.
Solution:
You can tell the driver that you have a bad card by using
an otherwise unused mem_end hexidecimal value of 0xbad at
boot time. You have to also supply a non-zero I/O base
for the card when using the 0xbad override. For example,
a card that is at 0x340 that doesn't ack the reset
would use something like:
LILO: linux ether=0,0x340,0,0xbad,eth0
This will allow the card detection to continue, even if your
card doesn't ACK the reset. If you are using the driver as
a module, then you can supply the option bad=0xbad just
like you supply the I/O address.
Problem:
NE*000 card hangs machine at first network access.
Reason:
This problem has been reported for kernels as old as 1.1.57
to the present. It appears confined to a few software configurable
clone cards. It appears that they expect to be initialized in
some special way.
Solution:
Several people have reported that running the supplied DOS
software config program and/or the supplied DOS driver prior
to warm booting (i.e. loadlin or the `three-finger-salute')
into linux allowed the card to work. This would indicate
that these cards need to be initialized in a particular
fashion, slightly different than what the present Linux
driver does.
Problem:
NE*000 ethercard at 0x360 doesn't get detected.
Reason:
Your NE2000 card is 0x20 wide in
I/O space, which makes it hit the parallel port at 0x378.
Other devices that could be there are the second floppy
controller (if equipped) at 0x370 and the secondary
IDE controller at 0x376--0x377.
If the port(s) are already registered by another driver, the
kernel will not let the probe happen.
Solution:
Either move your card to an address like 0x280, 0x340, 0x320
or compile without parallel printer support.
Problem:
Network `goes away' every time I print something (NE2000)
Reason:
Same problem as above, but you have an older kernel that
doesn't check for overlapping I/O regions. Use the
same fix as above, and get a new kernel while you are at it.
Problem:
NE*000 ethercard probe at 0xNNN: 00 00 C5 ... not found.
(invalid signature yy zz)
Reason:
First off, do you have a NE1000 or NE2000 card at the addr. 0xNNN?
And if so, does the hardware address reported look like a valid
one? If so, then you have a poor NE*000 clone. All NE*000 clones
are supposed to have the value 0x57 in bytes 14 and 15 of the
SA PROM on the card. Yours doesn't -- it has `yy zz' instead.
Solution:
There are two ways to get around this. The easiest is to
use an 0xbad mem_end value as described above for the
`no reset ack' problem. This will bypass the signature check,
as long as a non-zero I/O base is also given. This way no
recompilation of the kernel is required.
The second method (for hackers) involves changing the driver
itself, and then recompiling your kernel (or module).
The driver (/usr/src/linux/drivers/net/ne.c) has a "Hall of Shame"
list at about line 42. This list is used to detect poor clones.
For example, the DFI cards use `DFI' in the first 3 bytes of the
PROM, instead of using 0x57 in bytes 14 and 15, like they are
supposed to.
Problem:
The machine hangs during boot right after the `8390...' or
`WD....' message. Removing the NE2000 fixes the problem.
Solution:
Change your NE2000 base address to something like 0x340.
Alternatively, you
can use the ``reserve='' boot argument in conjunction with
the ``ether='' argument to protect the card from other
device driver probes.
Reason:
Your NE2000 clone isn't a good enough clone. An active
NE2000 is a bottomless pit that will trap any driver
autoprobing in its space.
Changing the NE2000 to a less-popular
address will move it out of the way of other autoprobes,
allowing your machine to boot.
Problem:
The machine hangs during the SCSI probe at boot.
Reason:
It's the same problem as above, change the
ethercard's address, or use the reserve/ether boot arguments.
Problem:
The machine hangs during the soundcard probe at boot.
Reason:
No, that's really during the silent SCSI probe, and it's
the same problem as above.
Problem:
NE2000 not detected at boot - no boot messages at all
Solution:
There is no `magic solution' as there can be a number of
reasons why it wasn't detected. The following list should
help you walk through the possible problems.
1) Build a new kernel with only the device drivers that you need.
Verify that you are indeed booting the fresh kernel. Forgetting to
run lilo, etc. can result in booting the old one. (Look closely at
the build time/date reported at boot.) Sounds obvious, but we have
all done it before. Make sure the driver is in fact included in
the new kernel, by checking the System.map file for names
like ne_probe.
2) Look at the boot messages carefully. Does it ever even mention
doing a ne2k probe such
as `NE*000 probe at 0xNNN: not found (blah blah)'
or does it just fail silently. There is a big difference.
Use dmesg|more
to review the boot messages after logging in, or hit Shift-PgUp
to scroll the screen up after the boot has completed and the login
prompt appears.
3) After booting, do a cat /proc/ioports and verify
that the full iospace that the card will require is vacant. If
you are at 0x300 then the ne2k driver will ask
for 0x300-0x31f. If any other device driver has registered
even one port anywhere in that range, the probe will not
take place at that address and will silently continue to the next
of the probed addresses. A common case is having the lp driver
reserve 0x378 or the second IDE channel reserve 0x376
which stops the ne driver from probing 0x360-0x380.
4) Same as above for cat /proc/interrupts. Make sure no
other device has registered the interrupt that you set
the ethercard for. In this case, the probe will happen, and the
ether driver will complain loudly at boot about not being able to
get the desired IRQ line.
5) If you are still stumped by the silent failure of the driver, then
edit it and add some printk() to the probe. For example, with the ne2k
you could add/remove lines (marked with a `+' or `-') in
linux/drivers/net/ne.c like:
int reg0 = inb_p(ioaddr);
+ printk("NE2k probe - now checking %x\n",ioaddr);
- if (reg0 == 0xFF)
+ if (reg0 == 0xFF) {
+ printk("NE2k probe - got 0xFF (vacant I/O port)\n");
return ENODEV;
+ }
Then it will output messages for each port address that it checks,
and you will see if your card's address is being probed or not.
6) You can also get the ne2k diagnostic from Don's ftp site (mentioned
in the howto as well) and see if it is able to detect your card after
you have booted into linux. Use the `-p 0xNNN' option to tell it
where to look for the card. (The default is 0x300 and it doesn't
go looking elsewhere, unlike the boot-time probe.)
The output from when it finds a card will look something like:
Checking the ethercard at 0x300.
Register 0x0d (0x30d) is 00
Passed initial NE2000 probe, value 00.
8390 registers: 0a 00 00 00 63 00 00 00 01 00 30 01 00 00 00 00
SA PROM 0: 00 00 00 00 c0 c0 b0 b0 05 05 65 65 05 05 20 20
SA PROM 0x10: 00 00 07 07 0d 0d 01 01 14 14 02 02 57 57 57 57
NE2000 found at 0x300, using start page 0x40 and end page 0x80.
Your register values and PROM values will probably be different.
Note that all the PROM values are doubled for a 16 bit card, and
that the ethernet address (00:00:c0:b0:05:65) appears in the
first row, and the double 0x57 signature appears at the
end of the PROM.
The output from when there is no card installed at 0x300
will look something like this:
Checking the ethercard at 0x300.
Register 0x0d (0x30d) is ff
Failed initial NE2000 probe, value ff.
8390 registers: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
SA PROM 0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
SA PROM 0x10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
Invalid signature found, wordlength 2.
The 0xff values arise because that is the value that
is returned when one reads a vacant I/O port. If you happen
to have some other hardware in the region that is probed, you
may see some non 0xff values as well.
7) Try warm booting into linux from a DOS boot floppy (via loadlin)
after running the supplied DOS driver or config program. It may be doing
some extra (i.e. non-standard) "magic" to initialize the card.
8) Try Russ Nelson's ne2000.com packet driver to see if even it can
see your card -- if not, then things do not look good. Example:
A:> ne2000 0x60 10 0x300
The arguments are software interrupt vector, hardware IRQ,
and I/O base. You can get it from any msdos archive in
pktdrv11.zip -- The current version may be newer than 11.
Problem:
You get messages such as the following:
eth0: bogus packet size: 65531, status=0xff, nxpg=0xff
Reason:
There is a shared memory problem.
Solution:
The most common reason for this is PCI machines that are
not configured to map in ISA memory devices. Hence you
end up reading the PC's RAM (all 0xff values) instead of
the RAM on the card that contains the data from the
received packet.
Other typical problems that are easy to fix are board conflicts,
having cache or `shadow ROM' enabled for that region, or
running your ISA bus faster than 8Mhz. There are also a
surprising number of memory failures on ethernet cards,
so run a diagnostic program if you have one for your
ethercard.
Problem:
SMC EtherEZ doesn't work in non-shared memory (PIO) mode.
Reason:
Older versions of the Ultra driver only supported the card
in the shared memory mode of operation.
Solution:
The driver in kernel version 2.0 and above also supports the
programmed I/O mode of operation. Upgrade to v2.0 or newer.
Problem:
Old wd8003 and/or jumper-settable wd8013 always get the IRQ wrong.
Reason:
The old wd8003 cards and jumper-settable wd8013 clones don't
have the EEPROM that the driver can read the IRQ setting from.
If the driver can't read the IRQ, then it tries to auto-IRQ
to find out what it is. And if auto-IRQ returns zero, then
the driver just assigns IRQ 5 for an 8 bit card or IRQ 10 for
a 16 bit card.
Solution:
Avoid the auto-IRQ code, and tell the kernel what the IRQ
that you have jumpered the card to in your module configuration
file (or via a boot time argument for in-kernel drivers).
Problem:
SMC Ultra card is detected as wd8013, but the IRQ and shared
memory base is wrong.
Reason:
The Ultra card looks a lot like a wd8013, and if the Ultra
driver is not present in the kernel, the wd driver may
mistake the ultra as a wd8013. The ultra probe comes before the
wd probe, so this usually shouldn't happen. The ultra stores
the IRQ and mem base in the EEPROM differently than a wd8013,
hence the bogus values reported.
Solution:
Recompile with only the drivers you need in the kernel. If you
have a mix of wd and ultra cards in one machine, and are using
modules, then load the ultra module first.
Problem:
The 3c503 picks IRQ N, but this is needed for some
other device which needs IRQ N. (eg. CD ROM driver, modem, etc.)
Can this be fixed without compiling this into the kernel?
Solution:
The 3c503 driver probes for a free IRQ line in the order
{5, 9/2, 3, 4}, and it should pick a line which isn't being
used. The driver chooses when
the card is ifconfig'ed into operation.
If you are using a modular driver, you can use module
parameters to set various things, including the IRQ value.
The following selects IRQ9, base
location 0x300, <ignored value>, and if_port #1 (the
external transceiver).
io=0x300 irq=9 xcvr=1
Alternately, if the driver is compiled into the kernel,
you can set the same values at boot by passing
parameters via LILO.
LILO: linux ether=9,0x300,0,1,eth0
The following selects IRQ3, probes for the base location,
<ignored value>, and the default if_port #0 (the internal
transceiver)
LILO: linux ether=3,0,0,0,eth0
Problem:
3c503: configured interrupt X invalid, will use autoIRQ.
Reason:
The 3c503 card can only use one of IRQ{5, 2/9, 3, 4}
(These are the only lines that are connected to the card.)
If you pass in an IRQ value that is not in the above
set, you will get the above message.
Usually, specifying an interrupt value for the 3c503 is
not necessary. The 3c503 will autoIRQ when it gets
ifconfig'ed, and pick one of IRQ{5, 2/9, 3, 4}.
Solution:
Use one of the valid IRQs listed above, or enable
autoIRQ by not specifying the IRQ line at all.
Problem:
The supplied 3c503 drivers don't use the AUI (thicknet) port.
How does one choose it over the default thinnet port?
Solution:
The 3c503 AUI port can be selected at boot-time for in-kernel
drivers, and at module insertion for modular drivers.
The selection is overloaded onto the low bit of
the currently-unused dev->rmem_start variable, so a boot-time
parameter of:
LILO: linux ether=0,0,0,1,eth0
should work for in-kernel drivers.
To specify the AUI port when loading as a module, just append
xcvr=1 to the module options line along with
your I/O and IRQ values.
Linux and ISA Plug and Play Ethernet Cards
For best results (and minimum aggravation) it is recommended
that you use the (usually DOS) program that came with your
card to disable the PnP mechanism and set it to a fixed
I/O address and IRQ. Make sure the I/O address you use is
probed by the driver at boot, or if using modules then supply
the address as an io= option in /etc/conf.modules.
You may also have to enter the BIOS/CMOS setup and mark the IRQ
as Legacy-ISA instead of PnP (if your computer has this option).
Note that you typically don't need DOS installed to run a
DOS based configuration program. You can usually just boot
a DOS floppy disk and run them from the supplied floppy disk.
You can also download OpenDOS and FreeDOS for free.
If you require PnP enabled for compatibility with some other
operating system then you will have to use the isapnptools
package with linux to configure the card(s) each time at boot.
You will still have to make sure the I/O address chosen for the
card is probed by the driver or supplied as an io= option.
Some systems have an `enable PnP OS' (or similar named)
option in the BIOS/CMOS setup menu which will need to
be disabled in nearly all cases or the cards won't
work properly, or even be detected . Best described by one
user who said `I don't know what it does behind the scenes,
but it seems to be evil.'
Ethercard is Not Detected at Boot.
The usual reason for this is that people are using a kernel
that does not have support for their particular card built
in. For a modular kernel, it usually means that the required
module has not been requested for loading, or that an I/O
address needs to be specified as a module option.
If you are using a modular based kernel, such as those installed
by most of the linux distributions, then try and use the
configuration utility for the distribution to select the module
for your card. For ISA cards, it is a good idea to determine
the I/O address of the card and add it as an
option (e.g. io=0x340) if the configuration utility asks
for any options. If there is no configuration utility, then
you will have to add the correct module name (and options)
to /etc/conf.modules -- see man modprobe for
more details.
If you are using a pre-compiled kernel that is part of
a distribution set, then check the documentation to see which
kernel you installed, and if it was built with support
for your particular card. If it wasn't, then your
options are to try and get one that has support
for your card, or build your own.
It is usually wise to build your own kernel with only
the drivers you need, as this cuts down on the kernel
size (saving your precious RAM for applications!) and
reduces the number of device probes that can upset
sensitive hardware. Building a kernel is not as complicated
as it sounds. You just have to answer yes or no to
a bunch of questions about what drivers you want, and
it does the rest.
The next main cause is having another device using part
of the I/O space that your card needs. Most cards are
16 or 32 bytes wide in I/O space. If your card is set
at 0x300 and 32 bytes wide, then the driver will ask
for 0x300-0x31f. If any other device driver has registered
even one port anywhere in that range, the probe will not
take place at that address and the driver will silently
continue to the next of the probed addresses. So, after
booting, do a cat /proc/ioports and verify that the
full I/O space that the card will require is vacant.
Another problem is having your card jumpered to an I/O
address that isn't probed by default. The list of
probed addresses for each driver is easily found just
after the text comments in the driver source.
Even if the I/O setting of your card is
not in the list of probed addresses, you can supply
it at boot (for in-kernel drivers) with
the ether= command as described in
Passing Ethernet Arguments...
Modular drivers can make use of the io= option
in /etc/conf.modules to
specify an address that isn't probed by default.
ifconfig reports the wrong I/O address for the card.
No it doesn't. You are just interpreting it incorrectly.
This is not a bug, and the numbers reported are correct. It just
happens that some 8390 based cards (wd80x3, smc-ultra, etc) have the
actual 8390 chip living at an offset from the first assigned I/O port.
This is the value stored in
dev->base_addr, and is what ifconfig reports. If you
want to see the full range of ports that your card uses, then try
cat /proc/ioports which will give the numbers you expect.
PCI machine detects card but driver fails probe.
Some PCI BIOSes may not enable all PCI cards at power-up,
especially if the BIOS option `PNP OS' is enabled. This
mis-feature is to support the current release of Windows which
still uses some real-mode drivers. Either disable this option,
or try and upgrade to a newer driver which has the code to
enable a disabled card.
Shared Memory ISA cards in PCI Machine do not work (0xffff)
This will usually show up as reads of lots of 0xffff values.
No shared memory cards of any type will work in a PCI machine
unless you have the PCI ROM BIOS/CMOS SETUP configuration set
properly. You have to set it to allow shared memory access
from the ISA bus for the memory region that your card is trying
to use. If you can't figure out which settings are applicable
then ask your supplier or local computer guru. For AMI BIOS,
there is usually a "Plug and Play" section where there will
be an ``ISA Shared Memory Size'' and ``ISA Shared Memory Base''
settings. For cards like the wd8013 and SMC Ultra, change the
size from the default of `Disabled' to 16kB, and change the base
to the shared memory address of your card.
Card seems to send data but never receives anything.
Do a cat /proc/interrupts.
A running total of the number of interrupt events your
card generates will be in the list given from the above.
If it is zero and/or doesn't increase when you try to use
the card then there is probably a physical interrupt
conflict with another device installed in the computer
(regardless of whether or not the other device has a
driver installed/available).
Change the IRQ of one of the two devices to a free IRQ.
Asynchronous Transfer Mode (ATM) Support
Werner Almesberger has been working on ATM support
for linux.
He has been working with the Efficient Networks ENI155p
board (
Efficient Networks)
and the Zeitnet ZN1221 board
(
Zeitnet).
Werner says that the driver for the ENI155p is rather
stable, while the driver for the ZN1221 is presently
unfinished.
Check the latest/updated status at the following URL:
Linux ATM Support
Gigabyte Ethernet Support
Is there any gigabyte ethernet support for Linux?
Yes, there are currently at least two.
A driver for the Packet Engines G-NIC PCI Gigabit Ethernet adapter
is available in the v2.0 and v2.2 kernels
For more details, support, and driver updates, see:
http://www.scyld.com/linux/drivers/yellowfin.html
The acenic.c driver available in the v2.2 kernels
can be used for the Alteon AceNIC Gigabit Ethernet card
and other Tigon based cards such as the 3Com 3c985.
The driver should also work on the NetGear GA620, however
this has yet to be verified.
FDDI Support
Is there FDDI support for Linux?
Yes. Larry Stefani has written
a driver for v2.0 with Digital's DEFEA (FDDI EISA)
and DEFPA (FDDI PCI) cards.
This was included into the v2.0.24 kernel. Currently
no other cards are supported though.
Full Duplex Support
Will Full Duplex give me 20MBps? Does Linux support it?
Cameron Spitzer writes the following about full duplex 10Base-T
cards: ``If you connect it to a full duplex switched hub,
and your system is fast enough and not doing much else, it can
keep the link busy in both directions.
There is no such thing as full duplex 10BASE-2 or 10BASE-5
(thin and thick coax).
Full Duplex works by disabling collision detection in the adapter.
That's why you can't do it with coax; the LAN won't run that way.
10BASE-T (RJ45 interface) uses separate wires for send and receive,
so it's possible to run both ways at the same time. The switching
hub takes care of the collision problem. The signalling rate
is 10 Mbps.''
So as you can see, you still will only be able to receive or
transmit at 10Mbps, and hence don't expect a 2x performance
increase. As to whether it is supported or not, that depends
on the card and possibly the driver. Some cards may do
auto-negotiation, some may need driver support, and some may
need the user to select an option in a card's EEPROM configuration.
Only the serious/heavy user would notice the difference between
the two modes anyway.
Ethernet Cards for Linux on SMP Machines
If you spent the extra money on a multi processor (MP) computer then
buy a good ethernet card as well. For v2.0 kernels it wasn't really
an issue, but it definitely is for v2.2. Most of the older
non-intelligent (e.g. ISA bus PIO and shared memory design) cards
were never designed with any consideration for use on a MP machine.
The executive summary is to buy an intelligent modern design
card and make sure the driver has been written (or updated) to
handle MP operation. (The key words here are `modern design' - the
PCI-NE2000's are just a 10+ year old design on a modern bus.)
Looking for the text spin_lock in the driver source is a good
indication that the driver has been written to deal with MP operation.
The full details of why you should buy a good card for MP use (and
what happens if you dont) follow.
In v2.0 kernels, only one processor was allowed `in kernel'
(i.e. changing kernel data and/or running device drivers) at any
given time. So from the point of view of the card (and the associated
driver) nothing was different from uni processor (UP) operation and
things just continued to work. (This was the easiest way to get a
working MP version of Linux - one big lock around the whole kernel
only allows one processor in at a time. This way you know that you
won't have two processors trying to change the same thing at the
same time!)
The downside to only allowing one processor in
the kernel at a time was that you only got MP performance
if the running programs were self contained and calculation intensive.
If the programs did a lot of input/output (I/O) such as reading or
writing data to disk or over a network, then all but one of the
processors would be stalled waiting on their I/O requests to be
completed while the one processor running in kernel frantically
tries to run all the device drivers to fill the I/O requests. The
kernel becomes the bottleneck and since there is only one processor
running in the kernel, the performance of a MP machine in the heavy
I/O, single-lock case quickly degrades close to that of a single
processor machine.
Since this is clearly less than ideal (esp. for file/WWW servers,
routers, etc.) the v2.2 kernels have finer grained locking - meaning
that more than one processor can be in the kernel at a time. Instead
of one big lock around the whole kernel, there are a lot of smaller
locks protecting critical data from being manipulated by more than
one processor at a time - e.g. one processor can be running the
driver for the network card, while another processor
is running the driver for the disk drive at the same time.
Okay, with that all in mind here are the snags: The finer locking
means that you can have one processor trying to send data
out through an ethernet driver while another processor tries to
access the same driver/card to do something else (such as get the
card statistics for cat /proc/net/dev). Oops - your card
stats just got sent out over the wire, while you got data for
your stats instead. Yes, the card got confused by being asked
to do two (or more!) things at once, and chances are it crashed
your machine in the process.
So, the driver that worked for UP is
no longer good enough - it needs to be updated with locks that
control access to the underlying card so that the three tasks of
receive, transmit and manipulation
of configuration data are serialized to
the degree required by the card for stable operation. The scary
part here is that a driver not yet updated with locks for stable
MP operation will probably appear to be working in a MP machine
under light network load, but will crash the machine or at least
exhibit strange behaviour when two (or more!) processors try to
do more than one of these three tasks at the same time.
The updated MP aware ethernet driver will (at a
minimum) require a lock
around the driver that limits access at the entry points
from the kernel into the driver to `one at a time please'.
With this in place, things will be serialized so that the
underlying hardware should be treated just as if it was being
used in a UP machine, and so it should be stable. The downside
is that the one lock around the whole ethernet driver has
the same negative performance implications that having one big
lock around the whole kernel had (but on a smaller scale) - i.e.
you can only have one processor dealing with the card
at a time.
[Technical Note: The performance impact may also include
increased interrupt latencies if the locks that need to be
added are of the irqsave type and they are held
for a long time.]
Possible improvements on this situation can be made in two
ways. You can try to minimize the time between when the lock is
taken and when it is released, and/or you can implement finer
grained locking within the driver (e.g. a lock around the whole
driver would be overkill if a lock or two protecting against
simultaneous access to a couple of sensitive registers/settings
on the card would suffice).
However, for older non-intelligent
cards that were never designed with MP use in mind, neither of
these improvements may be feasible. Worse yet is that the
non-intelligent cards typically require the processor to move
the data between the card and the computer memory, so in a
worst case scenario the lock will be held the whole time that
it takes to move each 1.5kB data packet over an ISA bus.
The more modern intelligent cards typically move network data
directly to and from the computer memory without any help from
a processor. This is a big win, since the lock is then only
held for the short time it takes the processor to tell the card
where in memory to get/store the next network data packet. More
modern card designs are less apt to require a single big
lock around the whole driver as well.
Ethernet Cards for Linux on Alpha/AXP PCI Boards
As of v2.0, only the 3c509, depca, de4x5, pcnet32, and all the
8390 drivers (wd, smc-ultra, ne, 3c503, etc.) have
been made `architecture independent' so as to work on the
DEC Alpha CPU based systems. Other updated PCI drivers from
Donald's WWW page may also work as these have been written
with architecture independence in mind.
Note that the changes that are required to make a driver
architecture independent aren't that complicated.
You only need to do the following:
-multiply all jiffies related values by HZ/100 to account
for the different HZ value that the Alpha uses.
(i.e timeout=2; becomes timeout=2*HZ/100;)
-replace any I/O memory (640k to 1MB) pointer dereferences with
the appropriate readb() writeb() readl() writel() calls, as
shown in this example.
- int *mem_base = (int *)dev->mem_start;
- mem_base[0] = 0xba5eba5e;
+ unsigned long mem_base = dev->mem_start;
+ writel(0xba5eba5e, mem_base);
-replace all memcpy() calls that have I/O memory as source or
target destinations with the appropriate one of
memcpy_fromio() or memcpy_toio().
Details on handling memory accesses in an architecture
independent fashion are documented in the file
linux/Documentation/IO-mapping.txt that comes
with recent kernels.
Ethernet for Linux on SUN/Sparc Hardware.
For the most up to date information on Sparc stuff, try the
following URL:
Linux Sparc Note that some Sparc ethernet hardware gets its MAC address
from the host computer, and hence you can end up with multiple
interfaces all with the same MAC address. If you need to
put more than one interface on the same net then use the
hw option to ifconfig to assign unique MAC address.
Issues regarding porting PCI drivers to the Sparc platform
are similar to those mentioned above for the AXP platform.
In addition there may be some endian issues, as the Sparc
is big endian, and the AXP and ix86 are little endian.
Ethernet for Linux on Other Hardware.
There are several other hardware platforms that Linux can
run on, such as Atari/Amiga (m68k). As in the Sparc case
it is best to check with the home site of each Linux
port to that platform to see what is currently supported.
(Links to such sites are welcome here - send them in!)
Linking 10 or 100 BaseT without a Hub
Can I link 10/100BaseT (RJ45) based systems together without a hub?
You can link 2 machines easily, but no more than that, without
extra devices/gizmos. See
Twisted Pair
-- it explains
how to do it. And no, you can't hack together a hub just by
crossing a few wires and stuff. It's pretty much impossible
to do the collision signal right without duplicating a hub.
SIOCSIFxxx: No such device
I get a bunch of `SIOCSIFxxx: No such device' messages at
boot, followed by a `SIOCADDRT: Network is unreachable'
What is wrong?
Your ethernet device was not detected at boot/module insertion
time, and when
ifconfig and route are run, they have no device
to work with. Use dmesg | more to review the
boot messages and see if there are any messages about
detecting an ethernet card.
SIOCSFFLAGS: Try again
I get `SIOCSFFLAGS: Try again' when I run `ifconfig' -- Huh?
Some other device has taken the IRQ that your ethercard
is trying to use, and so the ethercard can't use the IRQ.
You don't necessairly need to reboot to resolve this, as
some devices only grab the IRQs when they need them and
then release them when they are done. Examples are some
sound cards, serial ports, floppy disk driver, etc. You
can type cat /proc/interrupts to see which interrupts
are presently in use. Most of the
Linux ethercard drivers only grab the IRQ when they are
opened for use via `ifconfig'. If you can get the other
device to `let go' of the required IRQ line, then you
should be able to `Try again' with ifconfig.
Using `ifconfig' and Link UNSPEC with HW-addr of 00:00:00:00:00:00
When I run ifconfig with no arguments, it reports that
LINK is UNSPEC (instead of 10Mbs Ethernet) and it
also says that my hardware address is all zeros.
This is because people are running a newer version of
the `ifconfig' program than their kernel version. This
new version of ifconfig is not able to report these properties
when used in conjunction with an older kernel. You can either
upgrade your kernel, `downgrade' ifconfig, or simply ignore
it. The kernel knows your hardware address, so it really
doesn't matter if ifconfig can't read it.
You may also get strange information if the ifconfig
program you are using is a lot older than the kernel you are
using.
Huge Number of RX and TX Errors
When I run ifconfig with no arguments, it reports that I
have a huge error count in both rec'd and transmitted
packets. It all seems to work ok -- What is wrong?
Look again. It says RX packets big number PAUSE
errors 0 PAUSE dropped 0 PAUSE overrun 0.
And the same for the TX column.
Hence the big numbers you are seeing are the total number of
packets that your machine has rec'd and transmitted.
If you still find it confusing, try typing
cat /proc/net/dev instead.
Entries in /dev/ for Ethercards
I have /dev/eth0 as a link to /dev/xxx. Is this right?
Contrary to what you have heard, the files in /dev/* are not used.
You can delete any /dev/wd0, /dev/ne0 and similar entries.
Linux and ``trailers''
Should I disable trailers when I `ifconfig' my ethercard?
You can't disable trailers, and you shouldn't want
to. `Trailers' are a hack to avoid data copying in the
networking layers. The idea was to use a trivial
fixed-size header of size `H', put the variable-size header
info at the end of the packet, and allocate all
packets `H' bytes before the start of a page. While it was a
good idea, it turned out to not work well in practice.
If someone suggests the use of `-trailers', note that it
is the equivalent of sacrificial goats blood. It won't do
anything to solve the problem, but if problem fixes itself then
someone can claim deep magical knowledge.
Access to the raw Ethernet Device
How do I get access to the raw ethernet device in linux,
without going through TCP/IP and friends?
int s=socket(AF_INET,SOCK_PACKET,htons(ETH_P_ALL));
This gives you a socket receiving every protocol type.
Do recvfrom() calls to it and it will fill the sockaddr
with device type in sa_family and the device name in the
sa_data array. I don't know who originally invented
SOCK_PACKET for Linux (its been in for ages) but its superb stuff.
You can use it to send stuff raw too via sendto() calls.
You have to have root access to do either of course.
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