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From: Sergey Fedorov <serge.fdrv@gmail.com>
To: QEMU Developers <qemu-devel@nongnu.org>
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Richard Henderson" <rth@twiddle.net>,
	"Blue Swirl" <blauwirbel@gmail.com>,
	"Riku Voipio" <riku.voipio@iki.fi>
Subject: [Qemu-devel] tcg: How CPUState::current_tb is used?
Date: Mon, 2 May 2016 22:54:48 +0300	[thread overview]
Message-ID: <5727B088.1090400@gmail.com> (raw)

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Hi,

I can't figure out how this field is used. The comment says it's
"Currently executing TB", but actually it's the first TB in a chain of
TBs executed. Grep shows the only place it is really checked is
tb_invalidate_phys_page_range(). That code seems to be introduced long
ago in:

    commit ea1c18022edd0e2c45552d6fc2da6e15a3486b33
    Author: bellard <bellard@c046a42c-6fe2-441c-8c8c-71466251a162>
    Date:   Mon Jun 14 18:56:36 2004 +0000

        fixed self modifying code in case of asynchronous interrupt


I suspect it's only related to user emulation. But I would appreciate if
someone could give me an idea of how this really works :)

Thanks,
Sergey

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             reply	other threads:[~2016-05-02 19:55 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-02 19:54 Sergey Fedorov [this message]
2016-05-02 20:18 ` [Qemu-devel] tcg: How 'CPUState::current_tb' is used? Sergey Fedorov
2016-05-03  0:02   ` Peter Maydell
2016-05-03  9:56     ` Sergey Fedorov

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