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Date: Thu, 09 May 2013 12:26:22 +0200
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Subject: Re: [Qemu-devel] [PATCH 0/6] Drop the irredeemably racy
	cpu_unlink_tb()
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To: Michael Tokarev <mjt@tls.msk.ru>
Cc: Peter Maydell <peter.maydell@linaro.org>, Anthony Liguori <aliguori@us.ibm.com>, qemu-stable <qemu-stable@nongnu.org>, qemu-devel@nongnu.org, Alexander Graf <agraf@suse.de>, Blue Swirl <blauwirbel@gmail.com>, Paul Brook <paul@codesourcery.com>, Richard Henderson <rth@twiddle.net>

Am 09.05.2013 10:09, schrieb Michael Tokarev:
> 22.02.2013 22:09, Peter Maydell wrote:
>>   cpu-exec: wrap tcg_qemu_tb_exec() in a fn to restore the PC
>=20
> This needed a "back merge" of env+cpu states back to cpu.
> Maybe we should somehow revisit the whole concept of the
> two, because it's sorta fun: at some point all functions
> has been converted to accept `cpu' instead of `env', but
> in many places the first thing a function does is to
> get `env' pointer out of `cpu'.

The concept is really easy: There is so much CPU code around that for
many years no one dared to touch it, ;) so changes need to be done
incrementally - not only to identify any fallout! If one function is
converted to no longer rely on env, then rather likely in some caller it
still needs to convert from env -> cpu. Once that caller is converted
too, it goes on moving the conversion "outwards" until the only
remaining env functions are TCG-related. env access from a specific *CPU
type is cheap, thus only talking about common code here. You will find
more background on the big "QOM CPUState part X" series. CPU_COMMON is
definitely not the way for the future, it should be okay for backporting
though in this case.

Regards,
Andreas

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