[PATCH] S390: Remove support for lock elision.

[Stefan Liebler]

On 7/2/25 17:53, Adhemerval Zanella Netto wrote:
> 
> 
> On 01/07/25 06:39, Stefan Liebler wrote:
>> The support for TX lock elision of pthread mutexes on s390x is now removed.
>>
>> As already announced back in 2022 with z16, the used non-constrained
>> transactions are now not usable anymore on z17
>> (https://www.ibm.com/support/pages/system/files/inline-files/Tech%20Bytes%20May%202025%20zVM%207.4%20and%20IBM%20z17.pdf):
>> z16 Statement of Direction:
>> Removal of support of the transactional execution and constrained transactional
>> execution facility: In a future IBM Z hardware system family, the transactional
>> execution and constrained transactional execution facility will no longer be
>> supported.  Users of the facility on current servers should always check the
>> facility indications before use.
>>
>> z17 Support:
>> Reduced support for transactional execution (TX) - Non-constrained transactions
>> will result in unconditionally aborting with condition code 1 (CC1) and no TDB
>> stored.
> 
> I wonder if we still want to support it for x86 and powerpc.  If I
> recall correctly, x86 results are mixed and on some chips TSX was
> disabled in firmware to avoid some odd issues.  On POWER the kernel
> added PPC_FEATURE2_HTM_NOSC to avoid some odd ssues as well.
> 
Good question, but I can only decide it for s390x. Therefore this patch
only covers s390x.
Nevertheless, I've added the powerpc / x86_64 maintainers. Perhaps they
can decide for power and x86_64.

Thanks,
Stefan