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From: ebiederm@xmission.com (Eric W. Biederman)
To: Bernhard Walle <bwalle@suse.de>
Cc: x86@kernel.org, kexec@lists.infradead.org,
	Yinghai Lu <yhlu.kernel@gmail.com>,
	Vivek Goyal <vgoyal@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: Find offset for crashkernel reservation automatically
Date: Mon, 14 Jul 2008 02:44:37 -0700	[thread overview]
Message-ID: <m1od50ztoa.fsf@frodo.ebiederm.org> (raw)
In-Reply-To: <20080714112404.36783df5@halley.suse.de> (Bernhard Walle's message of "Mon, 14 Jul 2008 11:24:04 +0200")

Bernhard Walle <bwalle@suse.de> writes:

> * Yinghai Lu [2008-07-14 00:11]:
>>
>> should use min_t(u64, 1ULL<<32, max_low_pfn<<PAGE_SHIFT) replace ULONG_MAX
>
> Shouldn't we use  min_t(u64, ULLONG_MAX, max_low_pfn<<PAGE_SHIFT), i.e.
> should we really limit the crashkernel to a 32 bit address on a 64 bit
> system?

We should use the lowest physical address that meets our size and
alignment constraints.  However there is no reason to make this be <
4G or even < 1G.  The worst case is that we reserve an area the kdump
kernel can't run out of.  However /sbin/kexec should check for that as
the kexec on panic code is not necessarily a linux kernel.

Eric

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WARNING: multiple messages have this Message-ID (diff)
From: ebiederm@xmission.com (Eric W. Biederman)
To: Bernhard Walle <bwalle@suse.de>
Cc: "Yinghai Lu" <yhlu.kernel@gmail.com>,
	"Vivek Goyal" <vgoyal@redhat.com>,
	kexec@lists.infradead.org, x86@kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: Find offset for crashkernel reservation automatically
Date: Mon, 14 Jul 2008 02:44:37 -0700	[thread overview]
Message-ID: <m1od50ztoa.fsf@frodo.ebiederm.org> (raw)
In-Reply-To: <20080714112404.36783df5@halley.suse.de> (Bernhard Walle's message of "Mon, 14 Jul 2008 11:24:04 +0200")

Bernhard Walle <bwalle@suse.de> writes:

> * Yinghai Lu [2008-07-14 00:11]:
>>
>> should use min_t(u64, 1ULL<<32, max_low_pfn<<PAGE_SHIFT) replace ULONG_MAX
>
> Shouldn't we use  min_t(u64, ULLONG_MAX, max_low_pfn<<PAGE_SHIFT), i.e.
> should we really limit the crashkernel to a 32 bit address on a 64 bit
> system?

We should use the lowest physical address that meets our size and
alignment constraints.  However there is no reason to make this be <
4G or even < 1G.  The worst case is that we reserve an area the kdump
kernel can't run out of.  However /sbin/kexec should check for that as
the kexec on panic code is not necessarily a linux kernel.

Eric

  reply	other threads:[~2008-07-14  9:52 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-06-26 19:54 [PATCH] x86: Find offset for crashkernel reservation automatically Bernhard Walle
2008-06-26 19:54 ` Bernhard Walle
2008-06-27 13:32 ` Vivek Goyal
2008-06-27 13:32   ` Vivek Goyal
2008-06-27 13:42   ` Vivek Goyal
2008-06-27 13:42     ` Vivek Goyal
2008-06-27 14:06     ` Bernhard Walle
2008-06-27 14:06       ` Bernhard Walle
2008-06-27 14:19       ` Vivek Goyal
2008-06-27 14:19         ` Vivek Goyal
2008-06-27 14:22         ` Bernhard Walle
2008-06-27 14:22           ` Bernhard Walle
2008-06-27 18:00           ` Eric W. Biederman
2008-06-27 18:00             ` Eric W. Biederman
2008-06-27 18:29             ` Bernhard Walle
2008-06-27 18:29               ` Bernhard Walle
2008-07-03 13:14               ` Ingo Molnar
2008-07-03 13:14                 ` Ingo Molnar
2008-07-14  7:11   ` Yinghai Lu
2008-07-14  7:11     ` Yinghai Lu
2008-07-14  9:24     ` Bernhard Walle
2008-07-14  9:24       ` Bernhard Walle
2008-07-14  9:44       ` Eric W. Biederman [this message]
2008-07-14  9:44         ` Eric W. Biederman
2008-07-14 17:06         ` Yinghai Lu
2008-07-14 17:06           ` Yinghai Lu
2008-07-14 17:30           ` Eric W. Biederman
2008-07-14 17:30             ` Eric W. Biederman
2008-07-14 18:17             ` Yinghai Lu
2008-07-14 18:17               ` Yinghai Lu
2008-07-14 18:41               ` Eric W. Biederman
2008-07-14 18:41                 ` Eric W. Biederman
2008-07-14 18:47                 ` Bernhard Walle
2008-07-14 18:47                   ` Bernhard Walle
2008-07-14 18:55                   ` Eric W. Biederman
2008-07-14 18:55                     ` Eric W. Biederman
2008-07-14 19:08                     ` Yinghai Lu
2008-07-14 19:08                       ` Yinghai Lu

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