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[50.194.63.110]) by smtp.googlemail.com with ESMTPSA id d188sm12750714qkb.9.2016.03.28.15.12.32 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 28 Mar 2016 15:12:34 -0700 (PDT) Sender: Richard Henderson Subject: Re: [PATCH 1/8] tcg: Clean up direct block chaining data fields To: Paolo Bonzini , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Sergey Fedorov References: <1458815961-31979-1-git-send-email-sergey.fedorov@linaro.org> <1458815961-31979-2-git-send-email-sergey.fedorov@linaro.org> <87poukq9fk.fsf@linaro.org> <56F3F377.4070809@gmail.com> <87mvpnrkby.fsf@linaro.org> <56F4039A.5050907@redhat.com> Cc: sergey.fedorov@linaro.org, qemu-devel@nongnu.org, Peter Crosthwaite , Claudio Fontana , Andrzej Zaborowski , Aurelien Jarno , "Vassili Karpov (malc)" , Alexander Graf , Blue Swirl , Stefan Weil , qemu-arm@nongnu.org From: Richard Henderson Message-ID: <56F9AC4E.4070304@twiddle.net> Date: Mon, 28 Mar 2016 15:12:30 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <56F4039A.5050907@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-TUID: Mp+MH8rjcfYL On 03/24/2016 08:11 AM, Paolo Bonzini wrote: > There is also a case where a TB jumps to itself; it then appears twice > in the list with different values in the low bits, such as this: > > tb->jmp_list_first = tb | 0; > .--------------------' | > | .-------' > tb->jmp_list_next[0] = tb | 2; Of course, it begs the question of why TB would be in its own list, even if it does jump to itself. We only need the points-to list in order to invalidate a TB and unlink it. But if TB is being invalidated, we don't need to reset the jump within TB itself. r~ From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47121) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1akfOq-0002Gp-Dy for qemu-devel@nongnu.org; Mon, 28 Mar 2016 18:12:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1akfOp-0001tJ-Ll for qemu-devel@nongnu.org; Mon, 28 Mar 2016 18:12:40 -0400 Sender: Richard Henderson References: <1458815961-31979-1-git-send-email-sergey.fedorov@linaro.org> <1458815961-31979-2-git-send-email-sergey.fedorov@linaro.org> <87poukq9fk.fsf@linaro.org> <56F3F377.4070809@gmail.com> <87mvpnrkby.fsf@linaro.org> <56F4039A.5050907@redhat.com> From: Richard Henderson Message-ID: <56F9AC4E.4070304@twiddle.net> Date: Mon, 28 Mar 2016 15:12:30 -0700 MIME-Version: 1.0 In-Reply-To: <56F4039A.5050907@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/8] tcg: Clean up direct block chaining data fields List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Sergey Fedorov Cc: sergey.fedorov@linaro.org, Peter Crosthwaite , Stefan Weil , Claudio Fontana , qemu-devel@nongnu.org, Alexander Graf , Blue Swirl , qemu-arm@nongnu.org, "Vassili Karpov (malc)" , Aurelien Jarno On 03/24/2016 08:11 AM, Paolo Bonzini wrote: > There is also a case where a TB jumps to itself; it then appears twice > in the list with different values in the low bits, such as this: > > tb->jmp_list_first = tb | 0; > .--------------------' | > | .-------' > tb->jmp_list_next[0] = tb | 2; Of course, it begs the question of why TB would be in its own list, even if it does jump to itself. We only need the points-to list in order to invalidate a TB and unlink it. But if TB is being invalidated, we don't need to reset the jump within TB itself. r~