[Bug target/91135] New: __linux__ not defined with -mcall-aixdesc on 9.x and ppc64

[gcc at octaforge dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91135

            Bug ID: 91135
           Summary: __linux__ not defined with -mcall-aixdesc on 9.x and
                    ppc64
           Product: gcc
           Version: 9.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at octaforge dot org
  Target Milestone: ---

Since 9.x, using the `-mcall-aixdesc` makes gcc undefine `__linux__`. This
breaks compilation of the Linux kernel as it relies on the older behavior
(`-mcall-aixdesc` is used on BE, without it the kernel does not link and there
are several modules that check for `__linux__` being defined and break if it's
not).

The kernel claims it's a GCC bug:
https://bugzilla.kernel.org/show_bug.cgi?id=204125

Could someone confirm whether it is, so that it is known if this needs to be
fixed in gcc or in the kernel?

Thanks