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

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 6/3/19 10:11 AM, Paolo Bonzini wrote:
> On 31/05/19 18:54, Miroslav Rezanina wrote:
>> 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?
> 
> If you are not really going to use TCG, disabling SEMIHOSTING makes sense.
> 
> I think Philippe's patch are the right way to do it.
> 
> Perhaps CONFIG_SEMIHOSTING should be made "default y" and added as
> "#CONFIG_SEMIHOSTING=n" to default-configs/, but that's just cosmetic.

But then it is compiled/linked on target that don't care...

Oh, but this is also true currently:

$ fgrep -r qemu_semihosting_log_out
Binary file ppc-softmmu/qemu-system-ppc matches
...

What about:

  config SEMIHOSTING
      bool
      default n
      depends on !KVM

and keep specific targets using SEMIHOSTING=y

Using "default y" or "default y if !KVM" we have to add SEMIHOSTING=n on
all targets that don't care, which seems an incorrect use of Kconfig.

Aleksandar: Can we use SEMIHOSTING on KVM MIPS?

For ARM Peter said:

"semihosting hooks either SVC or HLT instructions, and inside
 KVM both of those go to EL1, ie to the guest, and can't be
 trapped to KVM."

Thanks,

Phil.