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Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is a
From: |
Alex Bennée |
Subject: |
Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available |
Date: |
Wed, 27 Jan 2021 12:34:48 +0000 |
User-agent: |
mu4e 1.5.7; emacs 28.0.50 |
Daniel P. Berrangé <berrange@redhat.com> writes:
> On Tue, Jan 26, 2021 at 05:24:10PM +0000, Alex Bennée wrote:
>>
>> Stefan Weil <sw@weilnetz.de> writes:
>>
>> > Am 25.01.21 um 23:35 schrieb Richard Henderson:
>> >> On 1/25/21 11:02 AM, Stefan Weil wrote:
>> >>> Am 25.01.21 um 20:02 schrieb Richard Henderson:
>> >>>> On 1/25/21 8:58 AM, Stefan Weil wrote:
>> >>>>> I have no evidence that TCI is less reliable than TCG, so I would not
>> >>>>> write
>> >>>>> that.
>> >>>> It can't pass make check-tcg.
>> >>> Where does it fail? Maybe an expected timeout problem which can be
>> >>> solved by
>> >>> increasing the timeouts for TCI?
>> >>>
>> >>> I have just run a local test of `make check-tcg` with native TCG and
>> >>> with TCI
>> >>> and did not see a difference. But I noticed that in both cases many
>> >>> tests show
>> >>> "skipped".
>> >> You need to enable docker or podman for your development, so that you get
>> >> all
>> >> of the cross-compilers.
>> >>
>> >> Then:
>> >>
>> >> TEST fcvt on arm
>> >> TODO ../qemu/tcg/tci.c:614: tcg_qemu_tb_exec()
>> >> ../qemu/tcg/tci.c:614: tcg fatal error
>> >> qemu: uncaught target signal 11 (Segmentation fault) - core dumped
>> >>
>> >> TEST float_convs on m68k
>> >> TODO ../qemu/tcg/tci.c:614: tcg_qemu_tb_exec()
>> >> ../qemu/tcg/tci.c:614: tcg fatal error
>> >> qemu: uncaught target signal 11 (Segmentation fault) - core dumped
>> >>
>> >> which is of course one of the TODO assertions.
>> >> It's positively criminal those still exist in the code.
>> >
>> >
>> > I installed podman and repeated `make check-tcg`. The log file still
>> > shows 87 lines with "SKIPPED". There is also a gdb core dump, several
>> > warnings, but nothing related to TCI. Both tests cited above seem to
>> > work without a problem.
>>
>> I'm going to go out on a limb and guess you have commit:
>>
>> 23a77b2d18 (build-system: clean up TCG/TCI configury)
>>
>> which temporarily has the effect of disabling TCI. See
>>
>> Subject: Re: [PATCH v4 1/4] configure: Fix --enable-tcg-interpreter
>> From: Paolo Bonzini <pbonzini@redhat.com>
>> Message-ID: <2b8b6291-b54c-b285-ae38-21f067a8497d@redhat.com>
>> Date: Mon, 25 Jan 2021 17:36:42 +0100
>>
>> with that fix fixed I see the same failures as Richard:
>>
>> ./qemu-arm ./tests/tcg/arm-linux-user/fcvt > /dev/null
>> TODO ../../tcg/tci.c:614: tcg_qemu_tb_exec()
>> ../../tcg/tci.c:614: tcg fatal error
>> qemu: uncaught target signal 11 (Segmentation fault) - core dumped
>> fish: “./qemu-arm ./tests/tcg/arm-linu…” terminated by signal SIGSEGV
>> (Address boundary error)
>>
>> which does raise the question before today when was the last time anyone
>> attempted to run check-tcg on this?
>>
>> > The complete log file is available from
>> > https://qemu.weilnetz.de/test/check-tcg.txt.
>> >
>> > Daniel, regarding your comment: TCI has 100 % test coverage for the
>> > productive code lines.
>>
>> By what tests? The fact you don't hit asserts in your day to day testing
>> doesn't mean there are features missing that are easily tripped up or
>> that TCI got it right.
>>
>> > All code lines which were never tested raise an
>> > assertion, so can easily be identified (and fixed as soon as there is a
>> > test case which triggers such an assertion). The known deficits are
>> > speed, missing TCG opcodes, unimplemented TCG opcodes because of missing
>> > test cases and missing support for some host architectures.
>>
>> Passing check-tcg would be a minimum for me.
>
> Passing check-tcg *in gitlab CI* would be the minimum to consider
> it on a par with TCG.
>
> The lack of automated GitLab CI for TCI is a reason my proposed wording
> described TCI as less reliable than native TCG. We can't claim it has
> equivalent reliability unless we have equiv automated testing of TCI.
I should point out that check-tcg is hardly a comprehensive test suite.
Most of our instruction testing for example tends to be done with RISU.
Any program that attempts to use vector instructions is likely to come a
cropper with TCI. I guess we don't even attempt to run check-acceptance
due to speed issues but it would be interesting to see how far it gets.
>
> Regards,
> Daniel
--
Alex Bennée
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, (continued)
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Richard Henderson, 2021/01/26
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Stefan Weil, 2021/01/27
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Richard Henderson, 2021/01/27
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Alex Bennée, 2021/01/27
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Stefan Weil, 2021/01/27
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Alex Bennée, 2021/01/27
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Stefan Weil, 2021/01/27
- qemu user mode fails to run programs with large VM / built with address sanitizer (was: Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available), Stefan Weil, 2021/01/28
- Re: qemu user mode fails to run programs with large VM / built with address sanitizer (was: Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available), Richard Henderson, 2021/01/28
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Daniel P . Berrangé, 2021/01/27
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available,
Alex Bennée <=
- Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available, Daniel P . Berrangé, 2021/01/26
Re: [PATCH v4 0/4] meson: Try to clarify TCG / TCI options for new users, Paolo Bonzini, 2021/01/29