Re: Proposal: Eliminate GFP_DMA

From: Martin J. Bligh (mbligh@aracnet.com)
Date: Fri Feb 28 2003 - 10:34:41 EST


>> > > umm. are you volunteering to convert drivers/net/macmace.c to the pci_*
>> > > API then? also, GFP_DMA is used on, eg, s390 to get memory below 2GB and
>> > > on ia64 to get memory below 4GB.
>> >
>> > The ia64 is a fine example of how broken it is. People have to hack around
>> > with GFP_DMA meaning different things on ia64 to everything else. It needs
>> > to die.
>>
>> At least on x86-64 it is still needed when you need have some hardware
>> with address limits < 4GB (e.g. an 24bit soundcard)
>>
>> pci_* on K8 only allows address mask 0xffffffff or unlimited.
>
> That's a bit broken... I have an ALS4000 PCI soundcard that is a 24-bit
> soundcard. pci_set_dma_mask should support 24-bits accordingly,
> otherwise it's a bug in your platform implementation... Nobody will be
> able to use certain properly-written drivers on your platform otherwise.

If we're going to really sort this out, would be nice to just pass an upper
bound for an address to __alloc_pages, instead of a simple bitmask ;-)

M.

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