From xen-devel-bounces@lists.xen.org Tue Nov 11 16:59:55 2014 Received: (at maildrop) by bugs.xenproject.org; 11 Nov 2014 16:59:55 +0000 Received: from lists.xen.org ([50.57.142.19]) by bugs.xenproject.org with esmtp (Exim 4.80) (envelope-from ) id 1XoEnL-0005JT-Rh for xen-devel-maildrop-Eithu9ie@bugs.xenproject.org; Tue, 11 Nov 2014 16:59:55 +0000 Received: from localhost ([127.0.0.1] helo=lists.xen.org) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1XoEdu-0008Lc-LH; Tue, 11 Nov 2014 16:50:10 +0000 Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1XoEds-0008LK-Qa for xen-devel@lists.xen.org; Tue, 11 Nov 2014 16:50:08 +0000 Received: from [85.158.143.35] by server-2.bemta-4.messagelabs.com id 4E/80-24532-04E32645; Tue, 11 Nov 2014 16:50:08 +0000 X-Env-Sender: julien.grall@linaro.org X-Msg-Ref: server-8.tower-21.messagelabs.com!1415724607!11981307!1 X-Originating-IP: [74.125.82.42] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 6.12.4; banners=-,-,- X-VirusChecked: Checked Received: (qmail 21658 invoked from network); 11 Nov 2014 16:50:07 -0000 Received: from mail-wg0-f42.google.com (HELO mail-wg0-f42.google.com) (74.125.82.42) by server-8.tower-21.messagelabs.com with RC4-SHA encrypted SMTP; 11 Nov 2014 16:50:07 -0000 Received: by mail-wg0-f42.google.com with SMTP id k14so11974860wgh.1 for ; Tue, 11 Nov 2014 08:50:07 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type :content-transfer-encoding; bh=Jk3IdSAToHYebBbPd7eR57KyUU1EgeuUyyQDi+F67JE=; b=iM9ENRQGRcLmdXXOtz/dyjUcmJujmDg2HMxZJOefwCqeEmpdzeKgHeTyVoLAkOqeT2 EDf2XFyX5VlnSDkZNr0C50s/qp/NRft4+U8mthQ4i9O8ZKKZfZXdT6F253GeoXXe9I88 B/vd9/AkR8D3E7+5m0BWOPzbxoCEhcKf51tNMcIz6bBuJXSnXdgI5p6MvCux/CqttLiU 593LWPNP3Fx0bZOPS9FljX8LFfsFVBvpcX5i7VcSNZ0OWiVNVXtkdibih1P/eSIDrRkx /ahjNQ4Sv5iX0gzWNWs0uIs4OASKjDHIPWgiSoadjn568yZtHg8FxDcc886CwcIe7wDx m7Ug== X-Gm-Message-State: ALoCoQkhRkv34MRlerEBx4cPEEne3BP/9dygJP9xIDbeFHoM4KDgnSntIgH/vwI/dC5Vzbc57Gjc X-Received: by 10.194.250.68 with SMTP id za4mr56662902wjc.92.1415724607322; Tue, 11 Nov 2014 08:50:07 -0800 (PST) Received: from Juliens-MacBook-Pro.local ([82.98.7.134]) by mx.google.com with ESMTPSA id d14sm27963938wjz.26.2014.11.11.08.50.06 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Nov 2014 08:50:06 -0800 (PST) Message-ID: <54623E3D.4060803@linaro.org> Date: Tue, 11 Nov 2014 17:50:05 +0100 From: Julien Grall User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Ian Campbell , Ian Jackson References: <1414579268.29975.13.camel@citrix.com> <1414579302-6692-18-git-send-email-ian.campbell@citrix.com> <21585.6188.366311.80971@mariner.uk.xensource.com> <1414672390.2064.31.camel@citrix.com> In-Reply-To: <1414672390.2064.31.camel@citrix.com> Cc: xen-devel@lists.xen.org, Stefano Stabellini Subject: Re: [Xen-devel] [PATCH OSSTEST v2 18/20] Osstest/Debian: Add "clk_ignore_unused" to default command line X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org Hi, Somehow I missed this email. On 30/10/2014 13:33, Ian Campbell wrote: > create ! > title it arm: domain 0 disables clocks which are in fact being used > thanks > > On Wed, 2014-10-29 at 16:39 +0000, Ian Jackson wrote: >> Ian Campbell writes ("[PATCH OSSTEST v2 18/20] Osstest/Debian: Add "clk_ignore_unused" to default command line"): >>> This stops dom0 from messing with clocks which it should and is required on >>> some platforms. It's harmless even when not needed. >> >> This is pretty odd. Doesn't this correspond to some kind of bug, in >> the dom0 kernel perhaps ? > > dom0 is not aware that some clocks are actually in use (e.g. by the > hypervisor), so the bug is probably in the lack of some interface to > communicate this from Xen to dom0, or some other mechanism to gate this. In reality, Xen is only using the clock of the UART. Even though, I think this would also happen with platform device passthrough. For the latter, it would be fairly easy via a PV drivers. But for UART... gating the clock could be a nightmare because every platform have their own way to enable/disable the clock. Futhermore, the clock could be shared with multiple device... I'm wondering if we could expose the UART to DOM0 without marking as disabled. It would avoid DOM0 to mess up the clock while everything would be catch via the vuart implementation in Xen. Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel