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SubjectRe: devfs / eth micro-problems
On Sun, Aug 13, 2000 at 04:25:44PM +0100, Alan Cox wrote:

> > ethernet cards had interchanged names. And indeed,
> > if I am not mistaken the 2.4.0-test2 change to eth_setup
> > causes the familiar ether=0,0,eth1 boot parameter to
> > assign the eth1 name to the first detected card.
> > I am inclined to consider this a buglet -
>
> Yes it would be a bug if so. It is meant to precisely emulate the old
> behaviour.

Ha, Alan - I see that you wrote to aeb@cwi.nl, but since halfway
this afternoon that site seems to be down, and also elsewhere
there are problems, but this guest account still works.

"It is meant to precisely emulate" - yes, but it doesn't.

Old situation:
For ethernet cards, drivers call
init_etherdev(NULL, sz);
drivers/net/net_init.c:init_etherdev() then calls
init_netdev(NULL, sz, "eth%d", ether_setup);
and this allocates space in init_alloc_dev(), and then
takes the first unused name in dev_alloc_name(), then
calls the setup function.
Thus, the name is assigned already when the setup function
is called, and the name assigned is independent of boot
parameters.

New situation:
Before allocating a name, init_netdev calls
netdev_boot_setup_check and this does some extremely
ugly junk. If the kernel was booted with parameters
for eth5 then this routine will assume that the first card
seen is called eth5 and assign the name and parameters
to this card.
Thus, in the new situation the numbering of the cards
depends on the boot parameters.

Indeed, a bug.

[Another strange thing is that net/ethernet/eth.c:eth_setup()
is precisely identical to net/core/dev.c:netdev_boot_setup().
It is __init, but still..]

Now this stuff by Pekka Riikonen was no doubt meant
to fix something, but I don't know what, so I'll
wait with sending a patch.

Andries


[PS - I keep a linux-kernel mail archive by copying,
each time I want to look at it, the recent stuff from
some archive site. Presently the only place I know about
that keeps unadulterated mails (no HTML junk added) is
ftp://ftp.uwsg.indiana.edu/mail.archive/kernel
but unfortunately I see that they threw out everything
before July 1st. No doubt someone can point me to a place
that has June 2000?]



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