Re: [PATCH v1 1/1] powerpc/papr_scm: Properly handle UUID types and API

[Vaibhav Jain]

Andy Shevchenko <andy.shevchenko@xxxxxxxxx> writes:

> On Thu, Apr 15, 2021 at 8:10 PM Vaibhav Jain <vaibhav@xxxxxxxxxxxxx> wrote:
>>
>>
>> Thanks for the patch Andy,
>>
>> Unfortunately ran into a compilation issue due to missing "#include
>> <asm/unaligned.h>" that provides definition for
>> get_unaligned_le64(). Gcc reported following error:
>>
>> error: implicit declaration of function ‘get_unaligned_le64’
>
> Right, I have not tested it (as mentioned in the comments to the patch)
>
>> After including the necessary header file, kernel compiled fine and I
>> was able to test & verify the patch.
>
> Thank you very much for the testing.
>
> I'm not sure what the coverage of your test is.

Your patch updates the way the interleaved set-cookies are populated in
papr_scm which are then used to populate label entry for a namespace. I
verified that the reported region setcookie hasnt changed for an nvdimm
region before and after applying your patch for both BE and LE variants:

# 64-bit Little endian kernel before applying the patch
$ sudo cat /sys/devices/ndbus0/region0/set_cookie
0x8b6b26cbc930e2b5

# 64-bit Little endian kernel after applying your patch
$ sudo cat /sys/devices/ndbus0/region0/set_cookie
0x8b6b26cbc930e2b5

# 64-bit Big endian kernel before applying your patch
$ sudo cat /sys/devices/ndbus0/region0/set_cookie
0x8b6b26cbc930e2b5

# 64-bit Big endian kernel after applying your patch
$ sudo cat /sys/devices/ndbus0/region0/set_cookie
0x8b6b26cbc930e2b5

> That's why I have an
> additional question below. Is the byte ordering kept the same in BE
> (32- and 64-bit) cases? Because I'm worrying that I might have missed
> something.
Libnvdimm store these cookies in label area as little endian values and
based on the results above I think we are good.
>
>
> -- 
> With Best Regards,
> Andy Shevchenko

-- 
Cheers
~ Vaibhav