Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available

[Alex Bennée]

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.

-- 
Alex Bennée