Re: [PATCH] kexec based hibernation: a prototype of kexec multi-stage load

From: ebiederm@xmission.com (Eric W. Biederman)
To: "Huang, Ying" <ying.huang@intel.com>
Cc: nigel@nigel.suspend2.net,
	Kexec Mailing List <kexec@lists.infradead.org>,
	linux-kernel@vger.kernel.org, "Rafael J. Wysocki" <rjw@sisk.pl>,
	Pavel Machek <pavel@ucw.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH] kexec based hibernation: a prototype of kexec multi-stage load
Date: Thu, 15 May 2008 19:55:44 -0700	[thread overview]
Message-ID: <m1tzgzez4f.fsf@frodo.ebiederm.org> (raw)
In-Reply-To: <1210904374.23707.178.camel@caritas-dev.intel.com> (Ying Huang's message of "Fri, 16 May 2008 10:19:34 +0800")

"Huang, Ying" <ying.huang@intel.com> writes:

> The disadvantage of this solution is that kernel B must know it is
> original kernel (A) or kexeced kernel (B). Different code should be used
> by kernel A and kernel B. And after jump from A to B, jump from B to A,
> when jump from A to B again, kernel A must use different code from the
> first time.

I don't know what the case is for keeping two kernels in memory and switching
between them.

I suspect a small piece of trampoline code between the two kernels could
handle the case. (i.e. purgatory pays attention).

That is a fundamental aspect of the design.  A general purpose infrastructure
with trampoline code to adapt it to whatever situation comes up.

Eric

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