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Re: what are the requirements on target/ code for -icount to work correc
From: |
Paolo Bonzini |
Subject: |
Re: what are the requirements on target/ code for -icount to work correctly? |
Date: |
Fri, 19 Jun 2020 13:16:34 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 |
On 19/06/20 07:46, Pavel Dovgalyuk wrote:
> I think, that we need some efforts from target maintainers to remove all such
> calls.
I'll take care of target/i386 (which does need one of the three
gen_io_end calls that are left).
>> Q2: is it a requirement that after an insn which is a "known
>> to be an I/O insn" one (like x86 in/out) and which is marked
>> up with gen_io_start()/gen_io_end() that we also end the TB?
>
> It is a requirement for instructions that access virtual clock/icount
> value (directly or not).
>
> There is also an assertion that can_do_io is enabled while generating an
> interrupt. I believe, that it doesn't affect RR, but is useful for
> deterministic icount mode.
As I understand it, the definition of "I/O insn" is anything that can
either:
- affect the icount deadline (e.g. by setting or removing a
QEMU_CLOCK_VIRTUAL timer)
- interrupt the current translation block with cpu_loop_exit,
cpu_restore_state or similar.
Paolo
- what are the requirements on target/ code for -icount to work correctly?, Peter Maydell, 2020/06/18
- Re: what are the requirements on target/ code for -icount to work correctly?, Pavel Dovgalyuk, 2020/06/19
- Re: what are the requirements on target/ code for -icount to work correctly?,
Paolo Bonzini <=
- Re: what are the requirements on target/ code for -icount to work correctly?, Peter Maydell, 2020/06/19
- Re: what are the requirements on target/ code for -icount to work correctly?, Paolo Bonzini, 2020/06/19
- Re: what are the requirements on target/ code for -icount to work correctly?, Peter Maydell, 2020/06/19
- Re: what are the requirements on target/ code for -icount to work correctly?, Paolo Bonzini, 2020/06/19
- Re: what are the requirements on target/ code for -icount to work correctly?, Peter Maydell, 2020/06/19
- Re: what are the requirements on target/ code for -icount to work correctly?, Alex Bennée, 2020/06/19
- Re: what are the requirements on target/ code for -icount to work correctly?, Peter Maydell, 2020/06/19
- Re: what are the requirements on target/ code for -icount to work correctly?, Max Filippov, 2020/06/22
- Re: what are the requirements on target/ code for -icount to work correctly?, Pavel Dovgalyuk, 2020/06/22