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From: Sergey Fedorov <serge.fdrv@gmail.com>
To: qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Peter Crosthwaite <crosthwaite.peter@gmail.com>,
	Aurelien Jarno <aurelien@aurel32.net>,
	Richard Henderson <rth@twiddle.net>
Subject: [Qemu-devel] exec: About DISAS_JUMP and DISAS_UPDATE
Date: Thu, 22 Oct 2015 21:28:58 +0300	[thread overview]
Message-ID: <56292AEA.3010408@gmail.com> (raw)

Hi all,

I am trying to understand what the difference should be between
DISAS_JUMP and DISAS_UPDATE. Actually, these macros have comments in
include/exec/exec-all.h which say that DISAS_JUMP should be used when
only PC was modified dynamically whereas DISAS_UPDATE should be used
when some other CPU state was (in addition to PC?) modified dynamically.
In fact, every target except ARM AArch64 does not distinguish between
them. As I can see ARM AArch64 seems to suppose that: (1) PC was not
modified when DISAS_UPDATE is used and should be updated with dc->pc
when finishing translation; (2) DISAS_JUMP can be used to indicate that
a new PC value was set and it should be preserved when finishing
translation.

So I'm a bit confused... What the difference should be? Maybe something
should be fixed/clarified to make the comments and the code consistent.

Best regards,
Sergey

             reply	other threads:[~2015-10-22 18:29 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-22 18:28 Sergey Fedorov [this message]
2015-10-22 19:50 ` [Qemu-devel] exec: About DISAS_JUMP and DISAS_UPDATE Richard Henderson
2015-10-22 21:28 ` Peter Maydell
2015-10-23 10:14   ` Sergey Fedorov
2015-10-23 11:10     ` Peter Maydell
2015-10-23 12:35       ` Sergey Fedorov
2015-10-23 12:37         ` Peter Maydell
2015-10-23 12:39           ` Sergey Fedorov
2015-10-23 12:41             ` Peter Maydell
2015-10-27 17:47               ` Sergey Fedorov

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