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From: "Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>
To: The development of GNU GRUB <grub-devel@gnu.org>
Subject: Re: [PATCH] powerpc: fix startup bss cleaning
Date: Tue, 16 Jul 2013 07:47:35 +0200	[thread overview]
Message-ID: <51E4DE77.40402@gmail.com> (raw)
In-Reply-To: <20130715151237.Horde.RWhdgZir309R5EmlUhPR2GA@imap.linux.ibm.com>

On 15.07.2013 21:12, Paulo Flabiano Smorigo/Brazil/IBM wrote:
> Hi,
>
> The trunk version of GRUB is crashing on power machines. Openfirmware
> returns the following message:
> Welcome to GRUB!
>
> DEFAULT CATCH!, exception-handler=fff00700
> at   %SRR0: 0000000000003940   %SRR1: 0000000000083002
> Open Firmware exception handler entered from non-OF code
>
> Client's Fix Pt Regs:
>   00 000000000020a074 0000000001a3ff40 0000000000000000 00000000001e3de0
>   04 00000000001e3eb0 0000000000000004 00000000001d1fd0 000000000000007c
>   08 0000000000004000 0000000000003940 00000000001d4810 0000000001a3ff40
>   0c 0000000040000084 0000000000000000 0000000000000000 0000000000000000
>   10 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>   14 0000000000c00000 0000000000000008 0000000000000000 0000000000000000
>   18 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>   1c 0000000000219620 00000000001e3eb0 0000000000219620 00000000001e3de0
> Special Regs:
>      %IV: 00000700     %CR: 20000084    %XER: 00000000  %DSISR: 00000000
>    %SRR0: 0000000000003940   %SRR1: 0000000000083002
>      %LR: 000000000020a0a4    %CTR: 0000000000003940
>     %DAR: 0000000000000000
> Virtual PID = 0
>   ok
> 0 >
>
> After some investigation, my colleague Gustavo Duarte discover that the
> problem is caused by grub_file_filters_enabled. Its initial value isn't
> zero:
> grub_file_filters_enabled[0]@0x219614 0x0
> grub_file_filters_enabled[1]@0x219618 0x0
> grub_file_filters_enabled[2]@0x21961c 0x0
> grub_file_filters_enabled[3]@0x219620 0x3940
>
>
> Using objdump I noticed that this variable is the last one from the bss
> section:
> $objdump -t grub-core/kernel.exec | sort
> ...
> 00218d14 l     O .bss   00000004 count.2347
> 00218d18 l     O .bss   00000100 buf.1909
> 00218e18 l     O .bss   00000100 linebuf
> 00218f18 g     O .bss   00000100 grub_errmsg
> 00219018 g     O .bss   00000010 grub_file_filters_all
> 00219028 g     O .bss   00000010 grub_file_filters_enabled
> 00219038 g       .bss   00000000 _end
>
> It seems that startup.S for powerpc skips the last bytes, so I made a
> patch to fix it. Tried again and the problem was gone:
> grub_file_filters_enabled[0]@0x219614 0x0
> grub_file_filters_enabled[1]@0x219618 0x0
> grub_file_filters_enabled[2]@0x21961c 0x0
> grub_file_filters_enabled[3]@0x219620 0x0
>
As discussed on IRC this patch was wrong. The real problem was handling 
unaligned BSS. Fixed in trunk now.
>
>
> Best regards!
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
>



      reply	other threads:[~2013-07-16  5:47 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-15 19:12 [PATCH] powerpc: fix startup bss cleaning Paulo Flabiano Smorigo/Brazil/IBM
2013-07-16  5:47 ` Vladimir 'φ-coder/phcoder' Serbinenko [this message]

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