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* [Qemu-devel] Fragile MAX_OP_PER_INSTR
@ 2008-04-22 10:19 Jan Kiszka
  2008-05-06 12:39 ` Edgar E. Iglesias
  0 siblings, 1 reply; 2+ messages in thread
From: Jan Kiszka @ 2008-04-22 10:19 UTC (permalink / raw)
  To: qemu-devel

Hi,

we ran into a weird SEGFAULT of QEMU which turned out to be a corruption
of tcg_ctx due to writing beyond gen_opc_buf. The reason for this was a
too small MAX_OP_PER_INSTR, given a particular toolchain (here the one
of SLES 10 for x86-32). So far it runs fine with

#define MAX_OP_PER_INSTR 64

Does anyone have an idea how to resolve the related comment in exec-all.h?

/* XXX: make safe guess about sizes */

Or should we just increase the safety margin?

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [Qemu-devel] Fragile MAX_OP_PER_INSTR
  2008-04-22 10:19 [Qemu-devel] Fragile MAX_OP_PER_INSTR Jan Kiszka
@ 2008-05-06 12:39 ` Edgar E. Iglesias
  0 siblings, 0 replies; 2+ messages in thread
From: Edgar E. Iglesias @ 2008-05-06 12:39 UTC (permalink / raw)
  To: Jan Kiszka; +Cc: qemu-devel

On Tue, Apr 22, 2008 at 12:19:06PM +0200, Jan Kiszka wrote:
> Hi,
> 
> we ran into a weird SEGFAULT of QEMU which turned out to be a corruption
> of tcg_ctx due to writing beyond gen_opc_buf. The reason for this was a
> too small MAX_OP_PER_INSTR, given a particular toolchain (here the one
> of SLES 10 for x86-32). So far it runs fine with
> 
> #define MAX_OP_PER_INSTR 64
> 
> Does anyone have an idea how to resolve the related comment in exec-all.h?
> 
> /* XXX: make safe guess about sizes */
> 
> Or should we just increase the safety margin?

Hi Jan,

I'm seeing this too, 64 seems to be enough for CRIS aswell. Unless someone has a better suggestion I think we should increase it.

Best regards
-- 
Edgar E. Iglesias
Axis Communications AB

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2008-04-22 10:19 [Qemu-devel] Fragile MAX_OP_PER_INSTR Jan Kiszka
2008-05-06 12:39 ` Edgar E. Iglesias

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