Re: [Xen-devel] [PATCH, RFC 1/4] linux: add new (replacement) mmap-batch ioctl

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> Ian Campbell <Ian.Campbell@xxxxxxxxxx> 11.01.10 16:12 >>>
>On Mon, 2010-01-11 at 14:49 +0000, Jan Beulich wrote:
>>  #define IOCTL_PRIVCMD_MMAPBATCH                                        \
>>         _IOC(_IOC_NONE, 'P', 3, sizeof(privcmd_mmapbatch_t))
>> +#define IOCTL_PRIVCMD_MMAP_BATCH                               \
>> +       _IOC(_IOC_NONE, 'P', 4, sizeof(privcmd_mmap_batch_t)) 
>
>Distinguishing the old vs new ioctl by only a _ in the middle seems a
>bit horrid. MMAPBATCH2 would at least be less prone to confusion...

Otoh it clearly tells that the two are very similar...

>Why not take the opportunity to make the ioctl (and hypercall?)
>interface 32 vs 64 agnostic by unconditionally using 64 bit sizes?

That's not common practice for structures containing pointers
afaict, and wouldn't be nice for the pointer type of 'arr' (would
double the array size on 32-bits for no reason, and would require
extra checking anyway).

Jan


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