Avi Kivity <avi@xxxxxxxxxx> writes:
>> -Capability: basic
>> +Capability: KVM_CAP_REG_LIST
>> Architectures: arm
>
> all
OK, I guess that's to be true in future. Fixed.
>> Type: vcpu ioctl
>> -Parameters: struct kvm_msr_list (in/out)
>> +Parameters: struct kvm_reg_list (in/out)
>> Returns: 0 on success; -1 on error
>> Errors:
>> - E2BIG: the msr index list is too big to fit in the array specified by
>> - the user.
>> + E2BIG: the reg index list is too big to fit in the array specified by
>> + the user (the number required will be written into n).
>>
>> struct kvm_msr_list {
>> - __u32 nmsrs; /* number of msrs in entries */
>> - __u32 indices[0];
>> + __u64 n; /* number of registers in reg[] */
>> + __u64 reg[0];
>> };
>>
>
> People complain that this interface is hard to use.
>
> How about supplying the address of the array (in addition to n) so you
> don't have to deal with variable sized arrays, and dropping E2BIG in
> favour of always updating n (n changed to something bigger than you had
> -> reallocate and rerun)
We re-write n anyway, *and* return -E2BIG. Not returning an error is
asking for trouble.
Passing an address in a struct is pretty bad, since it involves
compatibility wrappers. I don't think that is what makes the API hard
to use.
Cheers,
Rusty.
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