Re: Strange reboot behaviour (was Re: [patch] SMP fixes 2.2.1)

David Woodhouse (David.Woodhouse@mvhi.com)
Tue, 02 Feb 1999 11:46:25 +0000

eparis@ven.ra.rockwell.com said:
> I was having the same problem as you describe. It turned out to be
> the Ethernet adapter that was using DMA and continued to transfer
> packets from the wire to memory after a system reboot.

> I solved the problem by putting a "ifconfig eth0 down" just before the
> call to reboot in the corresponding rc script. Newer versions of
> sysvinit do this automatically.

This is not the correct answer. It only catches the case where network cards
do this. There are lots of other devices which use DMA.

A more sensible answer would be to have the card driver register a
reboot_notifier function, which disables the card just before reboot.

Is it possible to disable all DMA at the chipset level before rebooting, or do
we have to tell the cards directly?

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