From: "Alex Bennée" <alex.bennee@linaro.org>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: peter.maydell@linaro.org, qemu-devel@nongnu.org
Subject: Re: [RISU v2 14/17] Add magic and size to the trace header
Date: Wed, 20 May 2020 17:59:57 +0100 [thread overview]
Message-ID: <87v9kqfsoi.fsf@linaro.org> (raw)
In-Reply-To: <0cba90b4-e1c3-8cb9-a405-c5447a1aa17f@linaro.org>
Richard Henderson <richard.henderson@linaro.org> writes:
> On 5/18/20 7:53 PM, Richard Henderson wrote:
>> + if (master_header.magic != RISU_MAGIC ||
>> + master_header.risu_op != op ||
>> + master_header.size != extra_size) {
>> + res = RES_MISMATCH_HEAD;
>> + goto fail_header;
>> }
>
> Hmm. This isn't ideal.
>
> Consider e.g. an insn being tested that should pass, so master steps past the
> insn to the UDF and sends OP_COMPARE. But there's a bug in the emulator being
> tested so the apprentice gets SIGILL on the insn and so op ==
> OP_SIGILL.
In my experience this is one of the major failure modes as usually it's
a decode error or a -cpu version error that leads you to go astray.
That said most useful additional piece of information to dump would be
the insn word of the failing PC. We even know if one is on a RISU_OP and
one isn't so we can be a bit more expressive.
> So risu_op != op, but we only report the header difference.
>
> Perhaps that's good enough to understand the this particular problem, without
> the clutter of printing the rest of the reginfo frame -- at least if
> report_mismatch_header is improved to print risu_op names instead of numbers.
>
> Consider if master and apprentice are run with different --test-sve=<vq>
> values. That will produce a mismatch in size.
>
> Which could be a serious problem, if master_header.size > sizeof(master_ri) --
> we can't even receive the data. In that case, what I'm doing here printing the
> size mismatch is all that's possible.
>
> But suppose master_header.size <= sizeof(master_ri), so we can receive the
> data. So long as master_header.size == reginfo_size(&master_ri), then at least
> the data is self-consistent, and we *can* print out the difference in
> report_mismatch_reg(). Which in this case is going to be the difference in the
> two ri->sve_vl values. That difference is likely to be easiest to understand
> for the end user.
>
> I should probably split out this receive logic from
> recv_and_compare_register_info so that it can be reused by dump.
>
>
> r~
--
Alex Bennée
next prev parent reply other threads:[~2020-05-20 17:01 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 2:53 [RISU v2 00/17] risu cleanups and improvements Richard Henderson
2020-05-19 2:53 ` [RISU v2 01/17] Use bool for tracing variables Richard Henderson
2020-05-19 15:52 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 02/17] Unify master_fd and apprentice_fd to comm_fd Richard Henderson
2020-05-19 15:52 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 03/17] Hoist trace file opening Richard Henderson
2020-05-19 16:50 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 04/17] Adjust tracefile open for write Richard Henderson
2020-05-19 18:24 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 05/17] Use EXIT_FAILURE, EXIT_SUCCESS Richard Henderson
2020-05-19 18:24 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 06/17] Make some risu.c symbols static Richard Henderson
2020-05-19 18:25 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 07/17] Add enum RisuOp Richard Henderson
2020-05-19 18:39 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 08/17] Add enum RisuResult Richard Henderson
2020-05-19 19:06 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 09/17] Unify i/o functions and use RisuResult Richard Henderson
2020-05-20 15:50 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 10/17] Pass non-OK result back through siglongjmp Richard Henderson
2020-05-20 15:52 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 11/17] Always write for --master Richard Henderson
2020-05-20 16:12 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 12/17] Simplify syncing with master Richard Henderson
2020-05-20 16:14 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 13/17] Split RES_MISMATCH for registers and memory Richard Henderson
2020-05-20 16:25 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 14/17] Add magic and size to the trace header Richard Henderson
2020-05-19 21:16 ` Richard Henderson
2020-05-20 16:59 ` Alex Bennée [this message]
2020-05-19 2:53 ` [RISU v2 15/17] Compute reginfo_size based on the reginfo Richard Henderson
2020-05-20 17:30 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 16/17] aarch64: Reorg sve reginfo to save space Richard Henderson
2020-05-20 18:43 ` Alex Bennée
2020-05-19 2:53 ` [RISU v2 17/17] Add --dump option to inspect trace files Richard Henderson
2020-05-20 17:49 ` Alex Bennée
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