From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:35506) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RsiOr-0007Gf-FS for qemu-devel@nongnu.org; Wed, 01 Feb 2012 17:11:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RsiOp-0008QH-OF for qemu-devel@nongnu.org; Wed, 01 Feb 2012 17:11:33 -0500 Received: from mail-pw0-f45.google.com ([209.85.160.45]:38177) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RsiOp-0008Q3-Hb for qemu-devel@nongnu.org; Wed, 01 Feb 2012 17:11:31 -0500 Received: by pbaa11 with SMTP id a11so1881891pba.4 for ; Wed, 01 Feb 2012 14:11:30 -0800 (PST) Message-ID: <4F29B88E.4000508@codemonkey.ws> Date: Wed, 01 Feb 2012 16:11:26 -0600 From: Anthony Liguori MIME-Version: 1.0 References: <1326806593-21785-1-git-send-email-peter.maydell@linaro.org> In-Reply-To: <1326806593-21785-1-git-send-email-peter.maydell@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] exec.c: Clarify comment about tlb_flush() flush_global parameter List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: patches@linaro.org, qemu-devel@nongnu.org, =?UTF-8?B?6Zmz?= =?UTF-8?B?6Z+L5Lu7?= , Alexander Graf On 01/17/2012 07:23 AM, Peter Maydell wrote: > Clarify the comment about tlb_flush()'s flush_global parameter, > so it is clearer what it does and why it is OK that the implementation > currently ignores it. > > Signed-off-by: Peter Maydell Applied. Thanks. Regards, Anthony Liguori > --- > Minor clarification following a conversation on IRC... > > exec.c | 14 ++++++++++++-- > 1 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/exec.c b/exec.c > index 7f9f730..f667cf0 100644 > --- a/exec.c > +++ b/exec.c > @@ -1876,8 +1876,18 @@ static CPUTLBEntry s_cputlb_empty_entry = { > .addend = -1, > }; > > -/* NOTE: if flush_global is true, also flush global entries (not > - implemented yet) */ > +/* NOTE: > + * If flush_global is true (the usual case), flush all tlb entries. > + * If flush_global is false, flush (at least) all tlb entries not > + * marked global. > + * > + * Since QEMU doesn't currently implement a global/not-global flag > + * for tlb entries, at the moment tlb_flush() will also flush all > + * tlb entries in the flush_global == false case. This is OK because > + * CPU architectures generally permit an implementation to drop > + * entries from the TLB at any time, so flushing more entries than > + * required is only an efficiency issue, not a correctness issue. > + */ > void tlb_flush(CPUState *env, int flush_global) > { > int i;