Re: [Qemu-devel] [RFC PATCH 0/2] target: Build with CONFIG_SEMIHOSTING disabled

[Miroslav Rezanina <mrezanin@redhat.com>]

----- Original Message -----
> From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
> To: "Peter Maydell" <peter.maydell@linaro.org>
> Cc: "QEMU Developers" <qemu-devel@nongnu.org>, "Paolo Bonzini" <pbonzini@redhat.com>, "Miroslav Rezanina"
> <mrezanin@redhat.com>, "Richard Henderson" <richard.henderson@linaro.org>, "Aleksandar Rikalo"
> <arikalo@wavecomp.com>, "qemu-arm" <qemu-arm@nongnu.org>, "Aleksandar Markovic" <amarkovic@wavecomp.com>, "Aurelien
> Jarno" <aurelien@aurel32.net>, "Alex Bennée" <alex.bennee@linaro.org>, "Samuel Ortiz" <sameo@linux.intel.com>, "Rob
> Bradford" <robert.bradford@intel.com>
> Sent: Friday, May 31, 2019 6:40:30 PM
> Subject: Re: [RFC PATCH 0/2] target: Build with CONFIG_SEMIHOSTING disabled
> 
> On 5/31/19 6:21 PM, Peter Maydell wrote:
> > On Fri, 31 May 2019 at 16:47, Philippe Mathieu-Daudé <philmd@redhat.com>
> > wrote:
> >>
> >> Amusingly Miroslav and myself hit this issue at the same time.
> >>
> >> Currently there is no way to pass a CONFIG_X to sources in target/,
> >> except via a Makefile rule (and filling with stubs).
> >>
> >> Paolo says this is on purpose, CONFIG_X selectors are meant for
> >> devices and we try to avoid having config-devices.mak in
> >> config-target.h.
> > 
> > ...but some things in target/ are devices (like the Arm CPUs,
> > which inherit from TYPE_DEVICE).
> > 
> > Is there a way we can have a Kconfig fragment that expresses
> > "if you asked for an Arm CPU then this should 'select SEMIHOSTING'" ?
> 
> Yes, but inversely, we can also deselect a feature, and all features
> that requires it get deselected. My guess is Miroslav is building a
> KVM-only QEMU, but upstream does not allow to build ARM without TCG.
> 
> I'll see what happened to Samuel series "Support disabling TCG on ARM"
> and see if it can be salvaged:
> https://lists.gnu.org/archive/html/qemu-devel/2018-11/msg02451.html
> 
> I suppose in this thread:
> https://lists.gnu.org/archive/html/qemu-devel/2018-11/msg05641.html
> you refer to this series (not yet merged):
> https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg03137.html
> 
> I'll try to figure what "KVM injection of interrupts" is.
> 

What about CONFIG_ARM_VIRT - can we use it to introduce dependency on
CONFIG_SEMIHOSTING or is there valid scenario of qemu build with CONFIG_ARM_VIRT
enabled and CONFIG_SEMIHOSTING disabled?

Mirek
-- 
Miroslav Rezanina
Software Engineer - Virtualization Team Maintainer