[Bug 1821200] Re: Mark vx and vxe as important hwcap to be able to provide differently tuned shared libraries.

[Frank Heimes]

Just for completeness reasons - this ticket derived from discussions at
LP 1814796.

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Title:
  Mark vx and vxe as important hwcap to be able to provide differently
  tuned shared libraries.

Status in Ubuntu on IBM z Systems:
  New
Status in glibc package in Ubuntu:
  New

Bug description:
  Please pick the glibc commit "S390: Mark vx and vxe as important hwcap.". This commit is already cherry-picked to glibc 2.29 release branch: https://sourceware.org/git/?p=glibc.git;a=commit;h=6eb48fe80cb6dd3ef536e86d005976d1c22b170e.
  Note: This commit is also cherry-picked to glibc 2.27, 2.28 release branches.

  This commit allows to have a library (e.g. libatlas) with different
  tunings, e.g. one with vx- and another one with vxe-instructions. With
  this patch, glibc chooses the "best" available version depending on
  the hwcaps reported by the kernel.

  The correct locations for the different tuned libraries are:
  -for z14 with vxe-support: /usr/lib/s390x-linux-gnu/vxe/
  -for z13 with vx-support:  /usr/lib/s390x-linux-gnu/vx/
  -for all without vector-support: /usr/lib/s390x-linux-gnu/

  As information:
  One could also place the libraries into z13 or z14 subfolders. But e.g. if you run on a z13 and vector support is disabled (e.g. by specified kernel-parameter), the "z13" library with vector instructions is chosen - which is NOT allowed!
   
  Contact Information =   
   
  ---uname output---
   
   
  Machine Type =   
   
  ---Steps to Reproduce---
   see "problem description"
   
  Userspace tool common name: glibc 

  Userspace rpm: libc6 
   
  The userspace tool has the following bit modes: both 

  Userspace tool obtained from project website:  na 
   
  *Additional Instructions for  :
  -Attach ltrace and strace of userspace application.

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