On 24.11.14 12:35, Alex Bennée wrote: > > Fixed CC:kvmarm, Added: Alexander Graf, Fixed: my From: > > Replying to myself with additional information on each option > > Alex Bennée <alex.bennee@xxxxxxxxxx> writes: > >> Hi, >> >> I've almost finished the ARMv8 guest debug support but I have one >> problem left to solve. userspace needs to know how many hardware debug >> registers are available for GDB to use. This information is available >> from the ID_AA64DFR0_EL1 register. Currently I abuse GET_ONE_REG to >> fetch it's value however semantically this is poor as it's API is for >> getting guest state not host state and they could theoretically have >> different values. >> >> So far the options I've examined are: >> >> * 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. Btw, looking through the mess that we have today with asymmetric SET_GUEST_DEBUG and GET_DEBUGREGS ioctls I can't shake off the feeling that we're best off just doing all of the debug register sync via ONE_REGs. That way we at least have a guaranteed symmetric interface that can get and set values, so we won't trip over it on live migration. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
