linux-kernel - Re: [PATCH] Fix microcode-related suspend problem

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Message-ID: <20070331212337.GF14134@stusta.de>
Date:	Sat, 31 Mar 2007 23:23:37 +0200
From:	Adrian Bunk <bunk@...sta.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	LKML <linux-kernel@...r.kernel.org>,
	Tigran Aivazian <tigran@...azian.fsnet.co.uk>,
	Pavel Machek <pavel@....cz>, Maxim <maximlevitsky@...il.com>
Subject: Re: [PATCH] Fix microcode-related suspend problem

On Sat, Mar 31, 2007 at 01:35:32PM -0700, Andrew Morton wrote:
> On Sat, 31 Mar 2007 22:04:15 +0200 "Rafael J. Wysocki" <rjw@...k.pl> wrote:
> 
> > This patch appeard on LMKL six days ago and there have not been any negative
> > comments since then, so I think I can try to make it official.
> > 
> > ---
> > From: Rafael J. Wysocki <rjw@...k.pl>
> > 
> > Fix the regression resulting from the recent change of suspend code ordering
> > that causes systems based on Intel x86 CPUs using the microcode driver to
> > hang during the resume.
> > 
> > The problem occurs since the microcode driver uses request_firmware() in its
> > CPU hotplug notifier, which is called after tasks has been frozen and hangs.
> > It can be fixed by telling the microcode driver to use the microcode stored in
> > memory during the resume instead of trying to load it from disk.
> 
> CONFIG_SMP=n:
> 
> arch/i386/kernel/microcode.c: In function 'microcode_init_cpu':
> arch/i386/kernel/microcode.c:628: error: 'suspend_cpu_hotplug' undeclared (first use in this function)
> arch/i386/kernel/microcode.c:628: error: (Each undeclared identifier is reported only once
> arch/i386/kernel/microcode.c:628: error: for each function it appears in.)
> arch/i386/kernel/microcode.c: In function 'mc_sysdev_add':
> arch/i386/kernel/microcode.c:717: error: 'suspend_cpu_hotplug' undeclared (first use in this function)
> arch/i386/kernel/microcode.c: In function 'mc_sysdev_remove':
> arch/i386/kernel/microcode.c:745: error: 'suspend_cpu_hotplug' undeclared (first use in this function)
> 
> Given this, and the overall intrusiveness of the change, I'd worry about
> trying to get this into 2.6.21.

It fixes a regression, and we are still at least one month away from the 
release of 2.6.21.

2.6.20 was released with too many known regressions [1], let's not 
repeat this mistake with 2.6.21.

cu
Adrian

[1] at least the CONFIG_USB_SUSPEND powerdown regression and the
    pktcdvd+libata not working regression shouldn't have been in
    a released kernel

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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