Re: port-amd64/42980: satalink DMA fails under amd64

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

The following reply was made to PR port-amd64/42980; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: Julian Bourne <julian.bourne%gmail.com@localhost>
Cc: matthew green <mrg%eterna.com.au@localhost>, 
port-amd64-maintainer%NetBSD.org@localhost,
        gnats-admin%NetBSD.org@localhost, netbsd-bugs%NetBSD.org@localhost, 
gnats-bugs%NetBSD.org@localhost
Subject: Re: port-amd64/42980: satalink DMA fails under amd64
Date: Thu, 18 Mar 2010 17:11:04 +0100

 On Wed, Mar 17, 2010 at 09:59:58PM -0400, Julian Bourne wrote:
 > Quick update - just verified that your exact patch works
 > too Matthew - and its a good thing to have in there
 > anyway (target the 8192 boundary workaround at the
 > right chipset).
 > 
 > I'll let you and Manuel work out the right way to address
 > the 3112 - please keep me on the distribution - I'm
 > curious about the answer.
 > 
 > In the meantime, I looked into why the i386 isn't
 > exhibiting the problem - it looks like it might be because
 > the arch/x86/x86/bus_dma:_bus_dmamem_alloc_range()
 > function simply doesn't make the same check
 > (boundary >= size) as the xen implementation in arch/xen/x86/xen_bus_dma.c?
 > 
 > Which begs the question, should it? (given that
 > bus_dmamem_alloc man page implies its a not a legal
 > argument (and thanks for the awesome man pages by the
 > way - NetBSD rules)).
 
 I think I explicitely added this check because the hypervisor
 can't handle a boundary constraint explicitely, and the allocator
 will return a memory that fits the constraint only if boundary >= size
 (thanksfully the specs already said that :)
 
 -- 
 Manuel Bouyer <bouyer%antioche.eu.org@localhost>
      NetBSD: 26 ans d'experience feront toujours la difference
 --