From: Balbir Singh <bsingharora@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: <linuxppc-dev@ozlabs.org>,
alistair@popple.id.au, aneesh.kumar@linux.vnet.ibm.com
Subject: Re: [PATCH 2/2] powerpc: Fix crash at boot with CONFIG_PPC_RADIX_MMU=n
Date: Thu, 12 May 2016 11:32:36 +1000 [thread overview]
Message-ID: <20160512113236.58c0783d@cotter.ozlabs.ibm.com> (raw)
In-Reply-To: <1462949231-28355-2-git-send-email-mpe@ellerman.id.au>
On Wed, 11 May 2016 16:47:11 +1000
Michael Ellerman <mpe@ellerman.id.au> wrote:
> Currently a kernel that is built with CONFIG_PPC_RADIX_MMU=n, and then
> booted on a 64-bit Hash MMU system will crash on the first SLB miss,
> typically with an oops something like:
>
> Unrecoverable exception 4100 at c000000000969504
> cpu 0x0: Vector: 4100 at [c000000000de78e0]
> pc: c000000000969504: memmap_init_zone+0x160/0x2dc
> lr: c0000000009694b0: memmap_init_zone+0x10c/0x2dc
> ...
> [c000000000de7b60] c000000000968ec8 init_currently_empty_zone+0x3c/0x11c (unreliable)
> [c000000000de7bf0] c000000000969bc0 free_area_init_node+0x540/0x688
> [c000000000de7cf0] c000000000c4b3b4 free_area_init_nodes+0x7b4/0x864
> [c000000000de7df0] c000000000c2fce0 paging_init+0x88/0xa4
> [c000000000de7e60] c000000000c2b49c setup_arch+0x29c/0x2ec
> [c000000000de7f00] c000000000c23b7c start_kernel+0x88/0x524
> [c000000000de7f90] c000000000008c60 start_here_common+0x20/0xa0
>
> This is caused by the branch in slb_miss_realmode() that jumps directly
> to the unrecoverable case when MMU_FTR_RADIX is set:
>
> BEGIN_MMU_FTR_SECTION
> b 2f
> END_MMU_FTR_SECTION_IFSET(MMU_FTR_RADIX)
>
This makes sense and its a good way to avoid plenty of #ifdefs around code
Acked-by: Balbir Singh <bsingharora@gmail.com>
Balbir Singh
next prev parent reply other threads:[~2016-05-12 1:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-11 6:47 [PATCH 1/2] powerpc: Add mask of possible MMU features Michael Ellerman
2016-05-11 6:47 ` [PATCH 2/2] powerpc: Fix crash at boot with CONFIG_PPC_RADIX_MMU=n Michael Ellerman
2016-05-12 1:32 ` Balbir Singh [this message]
2016-05-12 2:29 ` Aneesh Kumar K.V
2016-05-12 2:28 ` [PATCH 1/2] powerpc: Add mask of possible MMU features Aneesh Kumar K.V
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