Re: [Qemu-devel] [Qemu-arm] [PATCH 03/13] target/arm/arm-semi: Make semihosting code hand out its own file descriptors

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> Currently the Arm semihosting code returns the guest file descriptors
> (handles) which are simply the fd values from the host OS or the
> remote gdbstub. Part of the semihosting 2.0 specification requires
> that we implement special handling of opening a ":semihosting-features"
> filename. Guest fds which result from opening the special file
> won't correspond to host fds, so to ensure that we don't end up
> with duplicate fds we need to have QEMU code control the allocation
> of the fd values we give the guest.
>
> Add in an abstraction layer which lets us allocate new guest FD
> values, and translate from a guest FD value back to the host one.
> This also fixes an odd hole where a semihosting guest could
> use the semihosting API to read, write or close file descriptors
> that it had never allocated but which were being used by QEMU itself.

I'm kind surprised QEMU doesn't already need this sort of facility for
something else. I guess virtfs and 9p have their own thing?
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Anyway:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

--
Alex Bennée