From: "H. Peter Anvin" <hpa@zytor.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vitaly Mayatskikh <v.mayatskih@gmail.com>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
Haren Myneni <hbabu@us.ibm.com>,
Neil Horman <nhorman@tuxdriver.com>,
Cong Wang <amwang@redhat.com>,
kexec@lists.infradead.org
Subject: Re: [PATCH 0/5] Add second memory region for crash kernel
Date: Thu, 22 Apr 2010 15:37:53 -0700 [thread overview]
Message-ID: <4BD0CFC1.2060907@zytor.com> (raw)
In-Reply-To: <m1aasvkupc.fsf@fess.ebiederm.org>
On 04/22/2010 03:07 PM, Eric W. Biederman wrote:
>
> Have you tried loading a 64bit vmlinux directly into a higher address
> range? There may be a bit or two missing but you should be able to
> load a linux kernel above 4GB. I tested the basics of that mechanism
> when I made the 64bit relocatable kernel.
>
> I don't buy the argument that there is a direct connection between
> the amount of memory you have and how much memory it takes to dump it.
> Even an indirect connections seems suspicious.
>
We actually have a 64-bit entry point even in bzImage; it is at offset
+0x200 from the 32-bit entry point. Right now that offset is not
exported anywhere, but it has been stable for a very long time... at
least for as far back as the decompressor has been 64 bits.
The interface to the 64-bit code is by necessity wider, since there is
no such thing as paging off in 64-bit mode, but it probably isn't *too*
hard to figure out how page tables need to be set up in order to work
properly. At that point, it would be good to document it.
-hpa
next prev parent reply other threads:[~2010-04-22 22:42 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-22 16:23 [PATCH 0/5] Add second memory region for crash kernel Vitaly Mayatskikh
2010-04-22 16:23 ` [PATCH 1/5] Introduce second memory resource " Vitaly Mayatskikh
2010-04-22 16:23 ` [PATCH 2/5] Modify parse_crashkernel* for new syntax Vitaly Mayatskikh
2010-04-22 16:23 ` [PATCH 3/5] Support second memory region in crash_shrink_memory() Vitaly Mayatskikh
2010-04-22 16:23 ` [PATCH 4/5] x86: use second memory region for dump-capture kernel Vitaly Mayatskikh
2010-04-22 16:23 ` [PATCH 5/5] kexec: update documentation Vitaly Mayatskikh
2010-04-22 22:07 ` [PATCH 0/5] Add second memory region for crash kernel Eric W. Biederman
2010-04-22 22:37 ` H. Peter Anvin [this message]
2010-04-22 22:45 ` Vivek Goyal
2010-04-23 0:48 ` Eric W. Biederman
2010-04-23 5:21 ` Cong Wang
2010-04-23 5:42 ` Eric W. Biederman
2010-04-23 6:43 ` Vitaly Mayatskikh
2010-04-23 14:44 ` Vivek Goyal
2010-04-23 7:08 ` Vitaly Mayatskikh
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