From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:40718) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TtgjC-0000fj-Kk for qemu-devel@nongnu.org; Fri, 11 Jan 2013 10:41:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ttgj9-0003Nw-33 for qemu-devel@nongnu.org; Fri, 11 Jan 2013 10:41:06 -0500 Received: from gecko.sbs.de ([194.138.37.40]:20969) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ttgj8-0003NW-PN for qemu-devel@nongnu.org; Fri, 11 Jan 2013 10:41:03 -0500 Message-ID: <50F03371.2000602@siemens.com> Date: Fri, 11 Jan 2013 16:44:49 +0100 From: Wolfgang Mauerer MIME-Version: 1.0 References: <1357911723-12688-1-git-send-email-wolfgang.mauerer@siemens.com> <50F02E67.4080804@suse.de> In-Reply-To: <50F02E67.4080804@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] Realview/Versatile: Export LED state List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= Cc: Peter Maydell , "qemu-devel@nongnu.org" , armbru@redhat.com, lcapitulino@redhat.com, "paul@codesourcery.com" , Aurelien Jarno On 11/01/13 16:23, Andreas F=C3=A4rber wrote: > Am 11.01.2013 16:00, schrieb Peter Maydell: >> On 11 January 2013 13:42, Wolfgang Mauerer wrote: >>> The configuration register for the onboard LEDs is >>> emulated, but the state is not exported, which makes >>> the feature not particularly useful. Create a character >>> device to make status changes accessible to the host. >>> >>> For example, use the command line argument >>> >>> -chardev socket,id=3Dleds,host=3Dlocalhost,port=3D12345,server,nowait >>> >>> to observe status changes via a socket. >> >> This isn't the only board we emulate which has LEDs. I'd >> rather see this problem tackled with a general plan for "this >> is how we handle LEDs in QEMU boards" rather than a >> versatile board specific patch. >=20 > Hm, mips_malta.c does use a CharDriverState... just a more "structured" > one using ASCII art. that's one of the reaons why I used a character device to export the status information. However, a simple custom protocol (or maybe the same information in JSON) seemed more appripriate since I assume that graphical frontends will eventually visualise the LED status. Having to parse some ASCII art output for this seems suboptimal. Exporting a binary QOM property (as you suggested in another email) might be an option, although I'm not really sure if LED status changes should be communicated this way -- to me, using a chardev feels nicer. Do the QMP maintainers have an opinion? Regards, Wolfgang