From: Simon Horman <horms@verge.net.au>
To: Jay Lan <jlan@sgi.com>
Cc: linux-ia64@vger.kernel.org, Bernhard Walle <bwalle@suse.de>,
Jack Steiner <steiner@sgi.com>,
kexec@lists.infradead.org, "Luck, Tony" <tony.luck@intel.com>
Subject: Re: [PATCH]IA64: assign a distinguishable label to uncached memory
Date: Mon, 15 Sep 2008 23:49:48 +0000 [thread overview]
Message-ID: <20080915234946.GA15167@verge.net.au> (raw)
In-Reply-To: <48CE96A0.80507@sgi.com>
On Mon, Sep 15, 2008 at 10:08:48AM -0700, Jay Lan wrote:
> Simon Horman wrote:
> > On Thu, Sep 11, 2008 at 04:00:08PM -0700, Jay Lan wrote:
> >> Currently a memory segment in memory map with attribute of EFI_MEMORY_UC
> >> is denoted as "System RAM" in /proc/iomem, while memory of attribute
> >> (EFI_MEMORY_WB|EFI_MEMORY_UC) is also labeled the same.
> >>
> >> The kexec utility then includes uncached memory as part of vmcore. The
> >> kdump kernel MCA'ed when it tries to save the vmcore to a disk. A normal
> >> "cached" access may cause MCAs.
> >>
> >> This patch would label memory with attribute of EFI_MEMORY_UC only as
> >> "Uncached RAM" so that kexec would know not to include it in the vmcore.
> >> I will submit a separate kexec-tools patch to the kexec list.
> >>
> >> Signed-off-by: Jay Lan <jlan@sgi.com>
> >
> > Hi Jay,
> >
> > I've taken a look on an RX2620, Tiger2 and Tiger4 and none of these
> > machines have EFI memory regions that are covered by this new check. That
> > is, any regions with the EFI_MEMORY_UC bit set in the attribute either also
> > have other attibute bits set, or are of a type not covered by this.
>
> Great! So the change affects most likely only SGI Altix machines.
> Below is the EFI memory regions of one node of an Altix machine:
>
> PAL_code 0000000001000000-0000000001FFFFFF 0000000000001000
> 8000000000000009
> MemMapIO 00000000FF000000-00000000FFFFFFFF 0000000000001000
> 8000000000000001
> Unusable 0000006000000000-000000600000FFFF 0000000000000010
> 0000000000000009
> RT_data 0000006000010000-00000060000FFFFF 00000000000000F0
> 8000000000001001
> BS_data 0000006000100000-00000060003FFFFF 0000000000000300
> 0000000000000001
> RT_data 0000006000400000-0000006001FFFFFF 0000000000001C00
> 8000000000001009
> RT_data 0000006002000000-0000006002FFFFFF 0000000000001000
> 8000000000000009
> BS_data 0000006003000000-0000006033DFFFFF 0000000000030E00
> 0000000000000009
> available 0000006033E00000-00000060F7FFFFFF 00000000000C4200
> 0000000000000009
> MemMapIO 0000008000000000-0000009FFFFFFFFF 0000000002000000
> 8000000000000003
>
> The first BS_data region starting at 0x0000006000100000 is the
> case. That memory is part of Altix "fetchop" space (AKA mspec).
>
> Since it does not affect IA64 machines you have, this patch should
> be very safe, yet needed for Altix.
Thats what I was hoping your reaction would be.
Acked-by: Simon Horman <horms@verge.net.au>
--
Simon Horman
VA Linux Systems Japan K.K., Sydney, Australia Satellite Office
H: www.vergenet.net/~horms/ W: www.valinux.co.jp/en
prev parent reply other threads:[~2008-09-15 23:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-11 23:00 [PATCH]IA64: assign a distinguishable label to uncached memory in Jay Lan
2008-09-12 7:55 ` [PATCH]IA64: assign a distinguishable label to uncached memory Bernhard Walle
2008-09-12 7:58 ` Bernhard Walle
2008-09-12 13:57 ` Jay Lan
2008-09-15 5:10 ` Simon Horman
2008-09-15 17:08 ` Jay Lan
2008-09-15 23:49 ` Simon Horman [this message]
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