Re: [PATCH] [1/4] x86_64: Fail dma_alloc_coherent on dma less devices

[Takashi Iwai <tiwai@suse.de>]

At Sat, 18 Aug 2007 21:03:25 +0200,
Andi Kleen wrote:
> 
> > Considering that the oops comes from this:
> > 
> >         /* Kludge to make it bug-to-bug compatible with i386. i386
> >            uses the normal dma_mask for alloc_coherent. */
> >         dma_mask &= *dev->dma_mask;
> 
> > 
> > and that that code is *old*, and comes from when this file was called 
> > arch/x86_64/kernel/pci-gart.c, and the comment doesn't seem to even be 
> 
> It might be outdated or it might now. The kludge was needed for Alsa because old
> i386 ignored the consistent mask and they didn't always set it correctly, but that 
> should be obsolete now? I'm not quite sure because sound devices
> are not always well tested on large memory systems which are the only
> ones who show this problem. Takashi, do you know if all alsa drivers
> set consistent mask correctly now?

Yes, ALSA driver set both masks from the very beginning :)

There are some OSS drivers still calling only pci_set_dma_mask().
Through a quick look, maybe only trident.c needs a fix because it uses
a mask < 32bit for ALI devices.  Others use 32bit DMA mask.


Takashi