Re: [Qemu-devel] [PATCH v5 12/20] trace: don't abort qemu if ftrace can't be initialized

[Stefan Hajnoczi]

On Wed, Sep 28, 2016 at 02:08:15PM +0100, Daniel P. Berrange wrote:
> If the ftrace backend is compiled into QEMU, any attempt
> to start QEMU while non-root will fail due to the
> inability to open /sys/kernel/debug/tracing/trace_on.

s/trace_on/tracing_on/

> 
> Add a fallback into the code so that it connects up the
> trace_marker_fd variable to /dev/null when setting
> EACCESS on the 'trace_on' file. This allows QEMU to
> run, with ftrace turned into a no-op.

I wonder whether a warning is appropriate.  It depends on the situation
because maybe QEMU was compiled with multiple backends and we don't care
about ftrace when it fails to initialize...

Stefan

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