From: Baoquan He <bhe@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Jiri Bohac <jbohac@suse.cz>, Toshi Kani <toshi.kani@hpe.com>,
David Airlie <airlied@linux.ie>, Dave Young <dyoung@redhat.com>,
joro@8bytes.org, kexec@lists.infradead.org,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
yinghai@kernel.org, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH v2] x86/kexec: Exclude GART aperture from vmcore
Date: Wed, 27 Dec 2017 20:44:29 +0800 [thread overview]
Message-ID: <20171227124429.GB15255@x1> (raw)
In-Reply-To: <20171227122523.GC13909@nazgul.tnic>
On 12/27/17 at 01:25pm, Borislav Petkov wrote:
> On Wed, Dec 27, 2017 at 03:44:49PM +0800, Baoquan He wrote:
> > > yes, instead of crashing the machine (because GART may be initialized in the
> > > 2nd kernel, overlapping the 1st kernel memory, which the 2nd kernel with its
> > > fake e820 map sees as unused).
> > >
> > > I'd say this is an improvement.
> >
> > I don't get what you said. If 'iommu=off' only specified in 1st kernel,
> > kdump kernel will think the memory which GART bar pointed as a hole.
> > This is incorrect. I don't see the improvement.
>
> So he says, this memory is unused. Why is that incorrect?!?
'iommu=off' specified in 1st kernel, that region will be normal memory,
there could be important kernel data written into the place. While kdump
kernel will take that region as a gart aperture, trying to read data
from that region will cause error which Jiri originally tried to fix.
WARNING: multiple messages have this Message-ID (diff)
From: Baoquan He <bhe@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Jiri Bohac <jbohac@suse.cz>, Toshi Kani <toshi.kani@hpe.com>,
David Airlie <airlied@linux.ie>,
yinghai@kernel.org, joro@8bytes.org, kexec@lists.infradead.org,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Dave Young <dyoung@redhat.com>, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH v2] x86/kexec: Exclude GART aperture from vmcore
Date: Wed, 27 Dec 2017 20:44:29 +0800 [thread overview]
Message-ID: <20171227124429.GB15255@x1> (raw)
In-Reply-To: <20171227122523.GC13909@nazgul.tnic>
On 12/27/17 at 01:25pm, Borislav Petkov wrote:
> On Wed, Dec 27, 2017 at 03:44:49PM +0800, Baoquan He wrote:
> > > yes, instead of crashing the machine (because GART may be initialized in the
> > > 2nd kernel, overlapping the 1st kernel memory, which the 2nd kernel with its
> > > fake e820 map sees as unused).
> > >
> > > I'd say this is an improvement.
> >
> > I don't get what you said. If 'iommu=off' only specified in 1st kernel,
> > kdump kernel will think the memory which GART bar pointed as a hole.
> > This is incorrect. I don't see the improvement.
>
> So he says, this memory is unused. Why is that incorrect?!?
'iommu=off' specified in 1st kernel, that region will be normal memory,
there could be important kernel data written into the place. While kdump
kernel will take that region as a gart aperture, trying to read data
from that region will cause error which Jiri originally tried to fix.
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next prev parent reply other threads:[~2017-12-27 12:44 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-16 0:15 [PATCH v2] x86/kexec: Exclude GART aperture from vmcore Jiri Bohac
2017-12-16 0:15 ` Jiri Bohac
2017-12-16 1:01 ` Baoquan He
2017-12-16 1:01 ` Baoquan He
2017-12-17 21:47 ` Borislav Petkov
2017-12-17 21:47 ` Borislav Petkov
2017-12-18 13:47 ` Baoquan He
2017-12-18 13:47 ` Baoquan He
2017-12-18 14:37 ` Borislav Petkov
2017-12-19 1:58 ` Baoquan He
2017-12-19 1:58 ` Baoquan He
2017-12-19 17:58 ` Jiri Bohac
2017-12-19 17:58 ` Jiri Bohac
2017-12-27 7:44 ` Baoquan He
2017-12-27 7:44 ` Baoquan He
2017-12-27 12:25 ` Borislav Petkov
2017-12-27 12:44 ` Baoquan He [this message]
2017-12-27 12:44 ` Baoquan He
2018-01-06 1:00 ` Jiri Bohac
2018-01-06 1:00 ` Jiri Bohac
2018-01-09 6:19 ` Baoquan He
2018-01-09 6:19 ` Baoquan He
2018-01-11 14:13 ` [tip:x86/mm] x86/gart: " tip-bot for Jiri Bohac
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