On 09/01/2012 03:35 PM, Rusty Russell wrote:
> 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.
Right, some s390 thing.
> I don't think that is what makes the API hard
> to use.
What is it then? I forgot what the original complaints/complainers were.
--
error compiling committee.c: too many arguments to function
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