Re: [PATCH] x86: {reverve,free}_memtype() take a physical address

[Rene Herman]

On 22-08-08 00:57, Pallipadi, Venkatesh wrote:
> > -----Original Message-----
> > From: Rene Herman [mailto:rene.herman@xxxxxxxxxxxx]
> > Sent: Thursday, August 21, 2008 3:27 PM
> > To: Pallipadi, Venkatesh
> > Cc: Ingo Molnar; Li, Shaohua; Dave Airlie; Yinghai Lu; Andreas
> > Herrmann; Arjan van de Ven; Linux Kernel; Siddha, Suresh B;
> > Thomas Gleixner; H. Peter Anvin; Dave Jones
> > Subject: Re: [PATCH] x86: {reverve,free}_memtype() take a
> > physical address
> >
> > On 22-08-08 00:16, Pallipadi, Venkatesh wrote:
> >
> > > Yes. Noticed that too and sent a patch here for x86/tip.
> > >
> > > http://www.ussg.iu.edu/hypermail/linux/kernel/0808.2/2270.html
> > >
> > > It is not very critical as it sounds as only set_memory_uc sets PAT
> > > bits for RAM pages. Most other users (devmem mmap, ioramep, pci)
> > > set PAT bits on the reserved memory. And there will not be conflicts
> > > across RAM and reserveed regions. Regardless, this was a stupid
> > > bug that we had missed earlier.
> > And unfortunately I don't think the above fully fixes it for
> > AGP. __pa()
> > gets the real physical address and the memtypes should be on the GART
> > remapped physical addresses it seems.
>
> Page being marked here as uncached is the page got from alloc_page().
> We are not really marking GART physical address as uncacheable. And
> that page returned from alloc_page is what we are tracking with
> reserve and free.
> IOW, the tracking is only to keep CPU accesses consistent across
> different va->pa and va across different CPUs and has nothing to do
> with GART physical address here.

Okay, if you say so... it _used_ to be before this array change to AGP 
that the GART addresses were in the memtype list, but I'll take your 
word for that being okay.

Rene
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