Date: Fri, 29 Dec 2023 21:31:10 +0100 From: Harry Schmalzbauer <freebsd@omnilan.de> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Dimitry Andric <dim@freebsd.org>, FreeBSD-STABLE <freebsd-stable@freebsd.org> Subject: Re: SIGILL when CPUTYPE set to anyting witjh avx and CFLAGS -O2 Message-ID: <e78df80b-f1b1-4297-b681-5db43e07bac0@omnilan.de> In-Reply-To: <ZY8qA7SKywXh_Yac@kib.kiev.ua> References: <accdf012-1b04-4227-9b0c-a78e94133fc2@omnilan.de> <72107B4B-F279-471B-8A8F-5B94C5EEDA47@FreeBSD.org> <62cc8fed-6acd-45fb-a138-ac7cd218191a@omnilan.de> <ZY8qA7SKywXh_Yac@kib.kiev.ua>
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On 12/29/23 21:20, Konstantin Belousov wrote:
> On Fri, Dec 29, 2023 at 09:12:35PM +0100, Harry Schmalzbauer wrote:
>> On 12/29/23 18:00, Dimitry Andric wrote:
>>> On 29 Dec 2023, at 11:14, Harry Schmalzbauer <freebsd@omnilan.de> wrote:
>>>>
>>>> at least since 14-release, I can't compile base/ports with CPUTYPE post nehalem. Any '-march' declaring AVX(*) capability leads to SIGILLing binaries with default -O2 CFLAGS.
>> ..
>>>>
>>>> If I compile without CFLAGS -O2 ("CFLAGS= -pipe"), -march=skylake-avx512 the binary doens't crash with SIGILL.
>>>>
>>>> Is CPUTYPE supposed to stay untouched these days?
>>>
>>> Obviously not, but are you sure your target CPU is correct? If it is not, the compiler may insert unsupported instructions.
>>
>> Ho Dimitry, thanks for your attention!
>> I have to admit that I know much too less about contemporary compilers and
>> CPUs likewise, but target CPU matches -march ;-)
>> I nailed it down to AVX instructions. Starting with 'sandybridge', Intel
>> CPUs provide avx instruction units, and starting with CPUTYPE?=sandybridge,
>> binaries crash on stable/14 (and late 14-current) on the corresponding
>> machines. But only in combination with CFLAGS -O2!
>>
>>
>>> In any case, for the above gdb session, try the command "disassemble" to see which particular instruction it crashed on. That may give more information.
>>
>> Thanks for the hint!
>> This came out:
>> Program terminated with signal SIGILL, Illegal instruction.
>> Privileged opcode.
>> #0 0x000000000041e040 in init_yank ()
>> (gdb) disassemble
>> Dump of assembler code for function init_yank:
>> 0x000000000041e030 <+0>: push %rbp
>> 0x000000000041e031 <+1>: mov %rsp,%rbp
>> 0x000000000041e034 <+4>: vpxor %xmm0,%xmm0,%xmm0
>> 0x000000000041e038 <+8>: vmovdqa -0x202c10(%rip),%xmm1 # 0x21b430
>> => 0x000000000041e040 <+16>: kxnorw %k0,%k0,%k1
> This is AVX512 instruction (some of it subset, probably F), not AVX.
>
...
>> Intel(R) Xeon(R) CPU E3-1275 v6 @ 3.80GHz (3800.00-MHz K8-class CPU)
My bad, sorry.
Confused machines. This indeed was wrong target CPU, stupid me.
Previously I tested tih CPUTYPE?=haswell, which editors/vim survives
currently.
Will run a base build with CPUTYPE?=haswell over the weekend and report
back.
Sorry for the noise so far...
-harry
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