From: Richard Henderson <rth@twiddle.net>
To: Peter Maydell <peter.maydell@linaro.org>,
QEMU Developers <qemu-devel@nongnu.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Pavel Dovgaluk <Pavel.Dovgaluk@ispras.ru>
Subject: Re: [Qemu-devel] when does a target frontend need to use gen_io_start()/gen_io_end() ?
Date: Tue, 12 May 2015 08:43:32 -0700 [thread overview]
Message-ID: <55521FA4.4080409@twiddle.net> (raw)
In-Reply-To: <CAFEAcA9JC4qUiHBbdXSpRZZtfPc7+Vu9vzd_3b87Zf-v9psfAQ@mail.gmail.com>
On 05/12/2015 08:32 AM, Peter Maydell wrote:
> In order for -icount to work, it's important for the target
> translate.c code to correctly bracket any generated code which
> can "do I/O" with gen_io_start()/gen_io_end() calls. But
> does anybody know exactly what the criteria are here for this?
> It would be nice if we could document this in a comment in
> gen_icount.h -- I'm happy to write one up if somebody will just
> tell me what the right answer is :-)
I'm really not sure.
So far I've assumed "i/o"-like insns, and those that can read some sort of
cycle counter. So while that handles easy cases like "inb" and "rdcc", it
certainly doesn't handle any target for which all i/o is memory mapped.
Which is sorta most of them these days, so the utility seems to be low...
r~
next prev parent reply other threads:[~2015-05-12 15:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-12 15:32 [Qemu-devel] when does a target frontend need to use gen_io_start()/gen_io_end() ? Peter Maydell
2015-05-12 15:43 ` Richard Henderson [this message]
2015-05-12 15:54 ` Peter Maydell
2015-05-12 18:17 ` Paolo Bonzini
2015-05-12 19:41 ` Peter Maydell
2015-05-13 8:42 ` Paolo Bonzini
2015-05-13 9:41 ` Peter Maydell
2015-05-13 10:03 ` Paolo Bonzini
2015-05-13 12:30 ` Frederic Konrad
2015-05-13 6:57 ` Pavel Dovgaluk
[not found] ` <16201.3286528692$1431500273@news.gmane.org>
2015-05-13 8:32 ` Paolo Bonzini
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