Re: [Qemu-devel] [PATCH 1/2] trace: allow trace events with string arguments

[Jan Kiszka <jan.kiszka@web.de>]

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On 2011-09-05 21:45, Blue Swirl wrote:
> On Mon, Sep 5, 2011 at 3:37 PM, Stefan Hajnoczi
> <stefanha@linux.vnet.ibm.com> wrote:
>> String arguments are useful for producing human-readable traces without
>> post-processing (e.g. stderr backend).  Although the simple backend
>> cannot handles strings all others can.  Strings should be allowed and
>> the simple backend can be extended to support them.
> 
> I don't think this is possible in general. Yes if the string can be
> found in the executable (assuming address space randomizations don't
> make that impossible post run), but not if the string happens to be
> constructed in the stack or in the data segment during run time.

Strings can be addressed in tracers like simpletrace by storing a
fixed-size copy (e.g. 64 chars) in the log. That will work out for the
majority of use cases.

Jan


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