[Cbe-oss-dev] ps3 kexec breakage in 2.6.24

[Geert Uytterhoeven]

On Thu, 10 Jan 2008, Jeremy Kerr wrote:
> I'm having trouble kexecing with the 2.6.24 rc kernels. 2.6.23 works 
> fine, but 2.6.24-rc1 and onwards don't work for me. The machine wedges 
> on the way down (I assume, as I don't get any output from the kexec-ed 
> kernel), with the framebuffer still showing the old kernel's console.
> 
> I've tried kexecing the same kernel, as well as kexecing a known-working 
> (ie, .23) kernel. Neither will work.

I assume you are using a mainline kernel source?

This is strange. We had a different kexec problem caused by the storage probe
thread keeping the storage notification device open (but the problematic code
is not yet in mainline), and after that got fixed, kexec works fine in Geoff's
tree.

At first sight, your lock-up scenario (and the 2 patches) look correct.

Can you please send me your .config?

> After bisecting, it seems this commit is causing the failure:
> 
> commit 0333d83509c7d8496c8965b5ba9bc0c98e83c259
> Author: Geert Uytterhoeven <Geert.Uytterhoeven at sonycom.com>
> Date:   Tue Oct 16 01:29:48 2007 -0700
> 
>     ps3fb: use fb_info.par properly
>     
>     ps3fb: Use fb_info.par properly:
>       o Move mode-specific fields into struct ps3fb_par
>       o Allocate struct ps3fb_par using framebuffer_alloc()
>       o Protect access to ps3fb_par in ps3fb_sync() using the console 
> semaphore
>         (this semaphore is already held when ps3fb_set_par() is called)
>       o Avoid calling ps3av_set_video_mode() if the actual video mode 
> hasn't
>         changed
>     
>     Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven at sonycom.com>
>     Cc: "Antonino A. Daplas" <adaplas at pol.net>
>     Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
>     Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
> 
> I see that this change introduces the acquire/release_console_sem() 
> calls - if I comment these out, the kernel can kexec.
> 
> Ben and I are just chasing up the uses of the console semaphore by 
> kexec, will let you know if we come up with anything.

With kind regards,

Geert Uytterhoeven
Software Architect

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