Re: [GIT PULL] x86/uapi for 3.8

[Markus Trippelsdorf]

On 2012.12.14 at 17:47 -0800, Linus Torvalds wrote:
> On Fri, Dec 14, 2012 at 5:41 PM, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> > I was wrong. It's not the x86 UAPI split, it's the DT pull. More people added.
> 
> Looking at the merge (just in case it could have done something odd),
> I'm starting to worry that this is some nasty heisenbug, and my
> bisection is not trustworthy at all. Because the DT pull sure as heck
> doesn't look like a likely candidate for anything either.
> 
> Ho humm. Anybody else see anything strange?

Yes. I'm seeing a BUG early during boot on my machine (RIP=NULL):
 
 BUG: unable to handle kernel NULL pointer dereference at           (null)

This is caused by:

commit 53b87cf088e2ea68d7c59619d0214cc15bb76133
Author: Matt Fleming <matt.fleming@xxxxxxxxx>
Date:   Fri Sep 7 18:23:51 2012 +0100

    x86, mm: Include the entire kernel memory map in trampoline_pgd
    
    There are various pieces of code in arch/x86 that require a page table
    with an identity mapping. Make trampoline_pgd a proper kernel page
    table, it currently only includes the kernel text and module space
    mapping.
    
    One new feature of trampoline_pgd is that it now has mappings for the
    physical I/O device addresses, which are inserted at ioremap()
    time. Some broken implementations of EFI firmware require these
    mappings to always be around.
    
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
    Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>

-- 
Markus
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