Re: Freeze Upon /dev/fd0 Use

Alan Cox (alan@lxorguk.ukuu.org.uk)
Wed, 2 Sep 1998 13:06:16 +0100 (BST)

> The good news is that ISA DMA is broken anyway, and it might just be an
> acceptable option to not even have a "BROKEN_DMA" config option, but
> just unconditionally refusing to allow two concurrent ISA DMA streams.
> The only things I know of that do ISA DMA is the floppy and old sound
> cards, and if that means that the sound skips while accessing the floppy
> I don't know if we really need to worry too much..

SCSI controllers, lance ethernet, sync cards, tape drives. Oh and of course
some sound cards use two DMA channels at the same time in full duplex
mode.

eg with a Z85230 card there are two DMA channels permanently allocated
and running all the time. The AHA1542 uses two (floppy and SCSI) etc

There isnt a general problem however since the floppy driver now claims to
support the command line option "nodma" on boot.

The first thing people should do however is make sure they have whatever
the up to date BIOS for their machine is if it is Triton based. There
were a small range of chipset bugs in triton which some early BIOS don't
know about and boards may need to disable (peer concurrency/streaming stuff)

Alan

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