Re: git: f1e8b0ff4e13 - main - bsd.cpu.mk: Add a workaround for erratum 843419

In reply to: Dima Panov : "Re: git: f1e8b0ff4e13 - main - bsd.cpu.mk: Add a workaround for erratum 843419"
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From: Mark Millard <marklmi_at_yahoo.com>
Date: Fri, 28 Aug 2026 15:10:55 UTC
On 8/28/26 03:55, Dima Panov wrote:
> Hello!
> 
> IMO, there must be additional guard knob to avoid apply extra LDFLAGS in
> test conditions
> 
> Something like:
> . if ${MACHINE_CPU:Mcortexa53} != "" && !defined AVOID_CORTEXA53_FIX
>  LDFLAGS += -Wl,--fix-cortex-a53-843419
> . endif

Official aarch64 FreeBSD OS builds/distributions never explicitly target
cortex-a53 to exclusion but aarch64 in general (armv8a): compatible with
all aarch64 CPUs, old and new, not just a specific old one. And they are
not built on systems that use cortext-a53 cpus. They do not even use
aarch64 cpus but instead cross build on amd64 cpus.

As for official port-package builds/distributions: they also normally do
not target cortex-a53 to exclusion but may target aarch64 in general
(armv8a). Such are normally built on aarch64 systems but not systems
that have cortex-a53 cpus.

So only use of unofficial builds generally can involved code targeted
only to cortex-a53 cpus.


As stands, outside clang/clang++ itself (and its tool chain), it is not
always simple to determine if aarch64 (armv8a or later) is what is being
targeted, especially when port-packages are involved. Also, rust and
other languages or compilers (and tool chains) may have the same type of
843419 issue independently of clang/clang++.

The existing cortex-a53 843419 handling breaks some rust builds
performed on aarch64 that do not target aarch64 at all (last I checked):
843419 does not apply to any such but is being specified anyway as it is
difficult to determine that the port is such a port.


> 
> 
> On 20.08.2026 19:30, Adrian Chadd wrote:
>> Do they or do they not have workarounds for the a53 bug in question?
>>
>> Like, ok, I can understand an issue like "rust/go is looking at LDFLAGS"
>> which is a whole fun bottle of wtf, but the end question I have here
>> is whether
>> rust/go have the workaround in question or not.
>>
>> Life may be easier if you live on later silicon without these bugs,
>> but we
>> live in a world where there's plenty of arm64 silicon revisions out there
>> all with different fun bugs and if we want to ship single kernel/
>> userland and
>> package builds for them all, we /do/ need to compile code that runs on
>> the least common denominator.
>>
>>
>>
>>
>> -adrian
>>
>> On Thu, 20 Aug 2026 at 08:41, Dima Panov <fluffy@freebsd.org> wrote:
>>>
>>> Hello!
>>>
>>> At least it badly affected aarch64 build on Apple Silicon in VMWare
>>> guest and always set LDFLAGS += -Wl,--fix-cortex-a53-843419
>>>
>>> However here is no cortex cores at all:
>>> $ dmesg | grep CPU
>>> Starting CPU 1 (10000)
>>> Starting CPU 2 (20000)
>>> Starting CPU 3 (30000)
>>> Starting CPU 4 (40000)
>>> Starting CPU 5 (50000)
>>> FreeBSD/SMP: Multiprocessor System Detected: 6 CPUs
>>> cpu0: <ACPI CPU> on acpi0
>>> CPU  0: Apple Unknown CPU r0p0 (midr: 610f0000) affinity:  0  0  0
>>> CPU  1: Apple Unknown CPU r0p0 (midr: 610f0000) affinity:  1  0  0
>>> CPU  2: Apple Unknown CPU r0p0 (midr: 610f0000) affinity:  2  0  0
>>> CPU  3: Apple Unknown CPU r0p0 (midr: 610f0000) affinity:  3  0  0
>>> CPU  4: Apple Unknown CPU r0p0 (midr: 610f0000) affinity:  4  0  0
>>> CPU  5: Apple Unknown CPU r0p0 (midr: 610f0000) affinity:  5  0  0
>>>
>>> Some rust and go ports now failed with error "flag provided but not
>>> defined: -Wl,--fix-cortex-a53-843419", see www/gitea or lang/rust-
>>> bootstrap for example
>>>
>>>
>>> On 14.07.2026 18:49, Andrew Turner wrote:
>>>> The branch main has been updated by andrew:
>>>>
>>>> URL: https://cgit.FreeBSD.org/src/commit/?
>>>> id=f1e8b0ff4e13b52c5e41a5eea3e686410af3dd0b
>>>>
>>>> commit f1e8b0ff4e13b52c5e41a5eea3e686410af3dd0b
>>>> Author:     Andrew Turner <andrew@FreeBSD.org>
>>>> AuthorDate: 2026-07-14 15:07:30 +0000
>>>> Commit:     Andrew Turner <andrew@FreeBSD.org>
>>>> CommitDate: 2026-07-14 15:47:15 +0000
>>>>
>>>>       bsd.cpu.mk: Add a workaround for erratum 843419
>>>>
>>>>       Add a workaround for the Arm Cortex-A53 erratum 843419. This
>>>> has been
>>>>       targeted when the build is either unoptimised for any CPU/
>>>> architecture
>>>>       or targets the Cortex-A53 or ARMv8.0 architecture.
>>>>
>>>>       PR:             296240
>>>>       PR:             296395
>>>>       Reported by:    Hal Murray <halmurray+freebsd@sonic.net>
>>>>       Reported by:    Andreas Schuh <x55839@icloud.com>
>>>>       Reviewed by:    cognet, mmel
>>>>       Sponsored by:   Arm Ltd
>>>>       Differential Revision:  https://reviews.freebsd.org/D58212
>>>> ---
>>>>    share/mk/bsd.cpu.mk | 18 +++++++++++++++++-
>>>>    1 file changed, 17 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/share/mk/bsd.cpu.mk b/share/mk/bsd.cpu.mk
>>>> index 33587b6ba25a..b743d3e71a36 100644
>>>> --- a/share/mk/bsd.cpu.mk
>>>> +++ b/share/mk/bsd.cpu.mk
>>>> @@ -6,7 +6,7 @@
>>>>    .if !defined(CPUTYPE) || empty(CPUTYPE)
>>>>    _CPUCFLAGS =
>>>>    . if ${MACHINE_CPUARCH} == "aarch64"
>>>> -MACHINE_CPU = arm64
>>>> +MACHINE_CPU = arm64 cortexa53
>>>>    . elif ${MACHINE_CPUARCH} == "amd64"
>>>>    MACHINE_CPU = amd64 sse2 sse mmx
>>>>    . elif ${MACHINE_CPUARCH} == "arm"
>>>> @@ -124,6 +124,14 @@ _CPUCFLAGS = -mcpu=${CPUTYPE}
>>>>    . elif ${MACHINE_ARCH:Mpowerpc64*} != ""
>>>>    _CPUCFLAGS = -mcpu=${CPUTYPE}
>>>>    . elif ${MACHINE_CPUARCH} == "aarch64"
>>>> +MACHINE_CPU = arm64
>>>> +.  if ${CPUTYPE} == "generic"
>>>> +MACHINE_CPU += cortexa53
>>>> +.  elif ${CPUTYPE} == "armv8-a"
>>>> +MACHINE_CPU += cortexa53
>>>> +.  elif ${CPUTYPE:M*cortex-a53*} != ""
>>>> +MACHINE_CPU += cortexa53
>>>> +.  endif
>>>>    .  if ${CPUTYPE:Marmv*} != ""
>>>>    # Use -march when the CPU type is an architecture value, e.g.
>>>> armv8.1-a
>>>>    _CPUCFLAGS = -march=${CPUTYPE}
>>>> @@ -302,6 +310,14 @@ MACHINE_CPU = riscv
>>>>    . endif
>>>>    .endif
>>>>
>>>> +########## arm64/aarch64
>>>> +.if ${MACHINE_CPUARCH} == "aarch64"
>>>> +# Add the Cortex-A53 erratum 843419 workaround if we are targeting it.
>>>> +. if ${MACHINE_CPU:Mcortexa53} != ""
>>>> +LDFLAGS += -Wl,--fix-cortex-a53-843419
>>>> +. endif
>>>> +.endif
>>>> +
>>>>    ########## arm
>>>>    .if ${MACHINE_CPUARCH} == "arm"
>>>>    MACHINE_CPU += arm
>>>
>>> -- 
>>> Sincerely,
>>> Dima (fluffy@FreeBSD.org, https://t.me/FluffyBSD, @fluffy:matrix-
>>> dev.freebsd.org)
>>> (desktop, kde, x11, office, ports-secteam)@FreeBSD team
>>>
> 


-- 
===
Mark Millard
marklmi at yahoo.com