Re: Exposing host debug capabilities to userspace

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

Alexander Graf <agraf@suse.de> writes:

>> Am 24.11.2014 um 13:32 schrieb Peter Maydell <peter.maydell@linaro.org>:
>> 
>>> On 24 November 2014 at 12:26, Alexander Graf <agraf@suse.de> wrote:
>>> On 24.11.14 12:35, Alex Bennée wrote:
>>>>> * KVM ioctl GET_ONE_REG(ID_AA64DFR0_EL1)
>>>> Nope, guest state API
>>> 
>>> What's the problem with using ONE_REG for this? After all, the total
>>> number of available guest debug register is a guest vcpu property of
>>> some sort.
>> 
>> Yes, but we don't want to know about properties of the guest
>> vCPU. In an ideal world QEMU could reserve say half the debug
>> registers for debugging the VM on startup and have KVM expose
>> ID registers indicating to the guest that it only had the
>> other half...
>
> Yup, so create another (read-only) ONE_REG that exposes the number of
> actual guest debug registers.

Does the GET/SET_ONE_REG have the concept of a read-only register? I'd
be worried by code just blindly iterating over the lists getting thrown
when one doesn't work.

>
> Alex
>
>> 
>> -- PMM

-- 
Alex Bennée