From: Andi Kleen <ak@muc.de>
To: Arjan van de Ven <arjanv@redhat.com>
Cc: linux-scsi@vger.kernel.org, gibbs@scsiguy.com
Subject: Re: aic7xxx strange code
Date: Fri, 02 Jan 2004 00:14:15 +0100 [thread overview]
Message-ID: <m3smizi7nc.fsf@averell.firstfloor.org> (raw)
In-Reply-To: <20040101223452.GA16369@devserv.devel.redhat.com> (Arjan van de Ven's message of "Thu, 1 Jan 2004 23:34:52 +0100")
Arjan van de Ven <arjanv@redhat.com> writes:
> On Thu, Jan 01, 2004 at 11:31:17PM +0100, Andi Kleen wrote:
>> Architecture pci_alloc_consistent uses
>> i386 normal dma mask
> .... but clipped to 32 bit
>
>> most 64bit archs/old x86-64 hardcoded 0xffffffff
>> newer IA64/some x86-64 consistent dma mask (2)
>> newest x86-64 normal dma mask & consistent dma mask (1) (2)
>> old redhat IA64 hardcoded 0xffffffffffffffff (?)
>
> not just old RH; At least one old SuSE too :0 (in fact I found a previous
> report claiming this only affected SuSE but it seems we're in the same boat
> now)
Ok. Old IA64 in general @) Or rather IA64/HP, right?
>>
>> (1) to be bug-to-bug compatible with i386, some drivers rely on that.
>> (2) consistent dma mask is normally equivalent to hardcoded 0xffffffff
>> because that is the default value
>>
>> It's quite a mess unfortunately. Due to (2) the 64bit architectures
>> are consistent, except for that old IA64. But i386 doing something
>> different is quite a problem.
>
> but i386 will *never* return > 32 bit at least.
The problem occurs with smaller masks than 32bit (e.g. used by some
sound drivers). The driver sets the normal mask < 32bit and expects
the memory to be allocated GFP_DMA. But it isn't.
The right thing to do would be to set the consistent mask, but that won't
work on i386 without an ifdef :-/
-Andi
prev parent reply other threads:[~2004-01-01 23:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-31 15:46 aic7xxx strange code Arjan van de Ven
2003-12-31 18:36 ` Justin T. Gibbs
2004-01-01 10:08 ` Arjan van de Ven
2004-01-01 16:16 ` Justin T. Gibbs
2004-01-01 16:17 ` Arjan van de Ven
2004-01-01 16:21 ` Justin T. Gibbs
2004-01-01 16:28 ` Arjan van de Ven
2004-01-01 22:31 ` Andi Kleen
2004-01-01 22:34 ` Arjan van de Ven
2004-01-01 23:14 ` Andi Kleen [this message]
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