Re: [Qemu-devel] TCG assertion with qemu-system-mipsel

[Yeongkyoon Lee <yeongkyoon.lee@samsung.com>]

On 03/05/2013 11:18 PM, Aurélien Jarno wrote:
> On Mon, Mar 04, 2013 at 05:37:31PM +0100, Aurélien Jarno wrote:
>> Hi,
>>
>> On Sat, Feb 23, 2013 at 11:10:18PM +0100, Stefan Weil wrote:
>>> This assertion occured with latest git master:
>>>
>>> qemu-system-mipsel: /src/qemu/tcg/tcg-op.h:2589:
>>>   tcg_gen_goto_tb: Assertion `(tcg_ctx.goto_tb_issue_mask & (1 << idx))
>>> == 0' failed.
>>> Aborted
>>>
>>> QEMU was built with --enable-debug and running a Debian MIPS Lenny (NFS
>>> root).
>>> The assertion happened when running "apt-get update" in the guest.
>>>
>> Is it something reproductible or more or less random? Have you Cc:ed
>> Richard because it's related to the latest patches?
>>
>> On my side I am experiencing random segfaults in various guests (at
>> least PowerPC, MIPS, SH4 and ARM). I have found a way to bisect it, even
>> if it is quite long (building Perl + the testsuite). Currently I know
>> that 1.3 is affected, while 1.2 is not.
>>
> I have found that the issue comes from the following commits, which
> unfortunately are not bisectable one by one (though it won't change the
> results a lot):
>
>      commit b76f0d8c2e3eac94bc7fd90a510cb7426b2a2699
>      Author: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
>      Date:   Wed Oct 31 16:04:25 2012 +0900
>      
>          tcg: Optimize qemu_ld/st by generating slow paths at the end of a block
>          
>          Add optimized TCG qemu_ld/st generation which locates the code of TLB miss
>          cases at the end of a block after generating the other IRs.
>          Currently, this optimization supports only i386 and x86_64 hosts.
>          
>          Signed-off-by: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
>          Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
>      
>      commit fdbb84d1332ae0827d60f1a2ca03c7d5678c6edd
>      Author: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
>      Date:   Wed Oct 31 16:04:24 2012 +0900
>      
>          tcg: Add extended GETPC mechanism for MMU helpers with ldst optimization
>          
>          Add GETPC_EXT which is used by MMU helpers to selectively calculate the code
>          address of accessing guest memory when called from a qemu_ld/st optimized code
>          or a C function. Currently, it supports only i386 and x86-64 hosts.
>          
>          Signed-off-by: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
>          Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
>      
>      commit 32761257c0b9fa7ee04d2871a6e48a41f119c469
>      Author: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
>      Date:   Wed Oct 31 16:04:23 2012 +0900
>      
>          configure: Add CONFIG_QEMU_LDST_OPTIMIZATION for TCG qemu_ld/st optimization
>          
>          Enable CONFIG_QEMU_LDST_OPTIMIZATION for TCG qemu_ld/st optimization only when
>          a host is i386 or x86_64.
>          
>          Signed-off-by: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
>          Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
>
> I will try to understand why.
>
>

Hi Aurélien,
Do you mean that those random segfaults occurred only when configured 
with "--enable-debug"?
Although I cannot see how my commits affect debug built image at a 
glance, I'll do double-check.
Thanks.