Re: [Qemu-arm] [Qemu-devel] [RFC PATCH 06/11] target/arm: use the common interface for WRITE0/WRITEC in arm-semi

[Peter Maydell]

On Fri, 31 May 2019 at 15:28, Alex Bennée <address@hidden> wrote:
> Miroslav Rezanina <address@hidden> writes:
> >From: "Alex Bennée" <address@hidden>
> >> OK - so from the upstream source tree CONFIG_SEMIHOSTING is still =y
> >> (but I can see most of them are now =n). Isn't the simplest solution to
> >> fix-up your version of the default_config file to include SEMIHOSTING?
> >>
> >
> > It's fix but it goes against our policy of handling CONFIG options so we
> > would prefer to have this fixed - otherwise there's no meaning in having
> > config option if you can't disable it.
>
> Is that what it means? For my part it means we don't build in
> CONFIG_SEMIHOSTING for the arches that don't need it (which we were
> before). Granted it only really simplified the vl.c parsing and dropped
> support for semihosting for the linux-user targets (except ARM).

Yes, that would be my interpretation of it. If we had
a 'config FOO' stanza for CPUs, then Arm CPUs would
"select SEMIHOSTING". If RedHat would like it to be possible
to build Arm CPUs without CONFIG_SEMIHOSTING then they're
free to submit patches for that, but that's a new feature
upstream doesn't currently support, not a bug in upstream.
(Also I'd be a bit dubious because it means that previously working
guest setups that use semihosting will break.)

PS: if we had a 'config FOO' stanza for CPUs that would also
allow us to say "building Arm CPUs requires the NVIC" and
similarly for things which in QEMU are devices but which are
architecturally tightly-coupled non-optional parts of the CPU.

thanks
-- PMM