tunables vs osxsave vs checkpointing vs _dl_runtime_resolve

[H.J. Lu]

On Thu, Mar 18, 2021 at 10:45 AM DJ Delorie <dj@redhat.com> wrote:
>
>
> "H.J. Lu" <hjl.tools@gmail.com> writes:
> > Please open a glibc bug and CC me.
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=27605
>

GLIBC_TUNABLES=glibc.cpu.hwcaps=-XSAVEC can be used to control it:

(gdb) r --direct
Starting program:
/export/build/gnu/tools-build/glibc-cet-gitlab/build-x86_64-linux/elf/tst-x86_64-1
--direct
[Inferior 1 (process 1499934) exited normally]
(gdb) b _dl_runtime_resolve_xsave
Breakpoint 1 at 0x7ffff7fe19d0: file ../sysdeps/x86_64/dl-trampoline.h, line 67.
(gdb) b _dl_runtime_resolve_xsavec
Breakpoint 2 at 0x7ffff7fe1aa0: file ../sysdeps/x86_64/dl-trampoline.h, line 67.
(gdb) r
Starting program:
/export/build/gnu/tools-build/glibc-cet-gitlab/build-x86_64-linux/elf/tst-x86_64-1
--direct

Breakpoint 2, _dl_runtime_resolve_xsavec ()
    at ../sysdeps/x86_64/dl-trampoline.h:67
67 _CET_ENDBR
(gdb) set env GLIBC_TUNABLES=glibc.cpu.hwcaps=-XSAVEC
(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program:
/export/build/gnu/tools-build/glibc-cet-gitlab/build-x86_64-linux/elf/tst-x86_64-1
--direct

Breakpoint 1, _dl_runtime_resolve_xsave ()
    at ../sysdeps/x86_64/dl-trampoline.h:67
67 _CET_ENDBR
(gdb)

-- 
H.J.