Re: mpt sets 64bit consistent mask yet requires mapping in same 4 GB chunk?!?

From: Jeremy Higdon <jeremy_at_sgi.com>
Date: 2004-02-14 10:08:09
On Fri, Feb 13, 2004 at 03:52:43PM -0700, Bjorn Helgaas wrote:
> On Friday 13 February 2004 2:30 pm, Jesse Barnes wrote:
> > On Fri, Feb 13, 2004 at 04:20:35PM -0500, Moore, Eric Dean wrote:
> > > I added pci_set_consistent_dma_mask() per request from
> > > Jeremy Higdon<jeremy@sgi.com> back on 12/03/03. He
> > > was having problems on a Altix (IA64) system. See
> > > attached email.  What is your recommendation? I have a mpt 
> > > patch in the queue which doesn't address this.
> > > 
> > > On Friday, February 13, 2004 9:12 AM, Alex Williamson wrote:
> > > > These are two perfectly valid consistent mappings as far as the
> > > > platform code is concerned.  I think mpt really needs to either set
> > > > a 32bit consistent map of do a single allocation when it requires
> > > > this type of thing.  Thanks,
> > 
> > I think Alex's second suggestion would be the best--do a single
> > allocation rather than falling back to a 32 bit consistent mask.
> 
> But even with a single allocation, there's nothing to prevent it
> from crossing a 4GB boundary, is there?

I don't think the Linux memory allocator will give back memory that
crosses a 32 bit boundary.

But I'm not an expert.  If I'm wrong, hopefully an expert will chime
in  :-)

jeremy
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Received on Fri Feb 13 18:19:10 2004

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