Re: [PATCH] x86-64: disable the GART before allocate aperture

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Friday 22 June 2007 22:33, Alan Cox wrote:
> On Fri, 22 Jun 2007 12:31:24 -0700
>
> Muli Ben-Yehuda <[email protected]> wrote:
> > On Fri, Jun 22, 2007 at 12:19:15PM -0700, Yinghai Lu wrote:
> > > [PATCH] x86-64: disable the GART before allocate aperture
> > >
> > > For K8 system: 4G RAM with memory hole remapping enabled, or more
> > > than 4G RAM installed. when mem is allocated for GART, it will do
> > > the memset for clear.  and for kexec case, the first kernel already
> > > enable that, the memset in second kernel will cause the system
> > > restart. So disable that at first before we try to allocate mem for
> > > it.
> >
> > Why does the memset in the second kernel cause a system restart?
>
> You've got mapped live gart pages from the previous kernel. Even if you
> disable the gart before a memset 

It's probably too late then. It could also interfere with other operations.
If anything the GART should be disabled during kexec shutdown. Perhaps we just 
need a suitable suspend function that does that. Eric, any preferences? 

> you may well have the video card using 
> gart translations and possibly live IOMMU mappings for devices using it
> via bus mastering - and those will cause you MCE exceptions with a
> corrupt cpu context flag (ie not nicely recoverable).

We disable those machine checks on K8 because they're not fully reliable.

-Andi
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux