[PATCH v2] cxl: Use fixed width predefined types in data structure.

[Michael Ellerman]

Frederic Barrat <fbarrat at linux.vnet.ibm.com> writes:

> Le 05/08/2016 à 14:02, Philippe Bergheaud a écrit :
>> 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).
>>
>> This patch also changes the size of the field data_size, and
>> makes it constant, to support 32-bit userland applications
>> running on big-endian ppc64 kernels transparently.
>>
>> This breaks the (young) API that has been merged in v4.8.
>>
>> Signed-off-by: Philippe Bergheaud <felix at linux.vnet.ibm.com>
>> ---
>> Changes since v1:
>>   Added an explanation for the proposed API change in the log.
>>
>> Note:
>> As far as I know, cxlflash is the only known user of the API.
>
>
> Yes, ideally, we'd like to change the type of 'data_size' to something 
> smaller/constant and were expecting it's still doable since the API was 
> merged to 4.8 and the expected user (cxlflash) hasn't started using the 
> API yet.

Yep that's fine, it just needed to be mentioned in the change log.

We don't guarantee that an ABI merged in -rc1 doesn't change in -rc2.
But we do (in general) guarantee that an ABI in a released kernel (ie.
4.8 final), never changes.

cheers