RE: [PATCH] cxl: Use fixed width predefined types in data structure.

[Michael Ellerman <mpe@ellerman.id.au>]

David Laight <David.Laight@ACULAB.COM> writes:

> From: Philippe Bergheaud
>> Sent: 04 August 2016 14:56
>> This patch fixes a regression introduced by commit b810253.
>> It substitutes the type __u8 to u8 in the uapi header cxl.h,
>> because the latter is not always defined in userland build
>> environments, in particular when cross-compiling libcxl on
>> x86_64 linux machines (RHEL6.7 and Ubuntu 16.04).
>> 
>> It also makes the definition of cxl_event_afu_driver_reserved
>> more consistent with the other definitions in the header file.
> ...
>> diff --git a/include/uapi/misc/cxl.h b/include/uapi/misc/cxl.h
>> index cbae529..180d526 100644
>> --- a/include/uapi/misc/cxl.h
>> +++ b/include/uapi/misc/cxl.h
>> @@ -136,8 +136,8 @@ struct cxl_event_afu_driver_reserved {
>>  	 *
>>  	 * Of course the contents will be ABI, but that's up the AFU driver.
>>  	 */
>> -	size_t data_size;
>> -	u8 data[];
>> +	__u32 data_size;
>> +	__u8 data[];
>>  };
>
> You've just changed 'data_size' from 64bit to 32bit (on 64bit systems).
> This isn't mentioned in the commit message and changes the API.

Yeah that's pretty fishy.

In practice I suspect there aren't thousands of users of that API, the
commit is only a month old, so we can probably still change it. But
please call it out in the change log.

cheers