Re: git: 6e93f5e4d693 - main - amd64: FRED support

On 7/20/26 17:51, Konstantin Belousov wrote:
> The branch main has been updated by kib:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=6e93f5e4d6932c423b89dff8fc08d86f8bdeb7b9
> 
> commit 6e93f5e4d6932c423b89dff8fc08d86f8bdeb7b9
> Author:     Konstantin Belousov <kib@FreeBSD.org>
> AuthorDate: 2026-02-13 11:24:40 +0000
> Commit:     Konstantin Belousov <kib@FreeBSD.org>
> CommitDate: 2026-07-20 21:51:02 +0000
> 
>      amd64: FRED support
>      
>      FRED support as defined starting from the SDM rev. 90, requires a new
>      'events' entry point to receive user and kernel mode exceptions and
>      interrupts notifications from the hardware.  A minimal asm trampoline is
>      enough, rest can be implemented in C due to the clean FRED organization
>      of the event reporting.
>      
>      The syscall entry is handled by a microptimized assembly path, directly
>      calling into the amd64_syscall() handler, instead of the generic events
>      entry point.
>      
>      Tested by:      emaste
>      Sponsored by:   The FreeBSD Foundation
>      MFC after:      1 week
>      Differential revision:  https://reviews.freebsd.org/D55829

This appears to have broken the cross-build jobs on GitHub for the past week
which build with clang 15 and clang 18.  Are those versions too old to support
the instructions used here?

Sample output:

--------------------------------------------------------------
>>> stage 3.1: building everything
--------------------------------------------------------------
/home/runner/work/freebsd-src/freebsd-src/sys/amd64/amd64/exception.S:1455:2: error: invalid instruction mnemonic 'eretu'
  eretu
  ^~~~~
/home/runner/work/freebsd-src/freebsd-src/sys/amd64/amd64/exception.S:1521:2: error: invalid instruction mnemonic 'lkgs'
  lkgs %ax
  ^~~~
/home/runner/work/freebsd-src/freebsd-src/sys/amd64/amd64/exception.S:1542:2: error: invalid instruction mnemonic 'eretu'
  eretu
  ^~~~~
/home/runner/work/freebsd-src/freebsd-src/sys/amd64/amd64/exception.S:1662:2: error: invalid instruction mnemonic 'erets'
  erets
  ^~~~~
/home/runner/work/freebsd-src/freebsd-src/sys/amd64/amd64/exception.S:1682:2: error: invalid instruction mnemonic 'erets'
  erets
  ^~~~~
--- exception.o ---
*** [exception.o] Error code 1

(Or maybe clang needs some -m<foo> or .set <foo> to enable use of these instructions?)

-- 
John Baldwin