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Wed, 28 Aug 2019 17:31:45 +0000 From: Aleksandar Markovic To: Laurent Vivier , Josh Kunz , Aleksandar Markovic , "milos.stojanovic@rt-rk.com" , Petar Jovanovic Thread-Topic: [EXTERNAL]Re: [Qemu-devel] patch to swap SIGRTMIN + 1 and SIGRTMAX - 1 Thread-Index: AQHVWALJmqy0WHd9B0ClDA0tDggZvacN9W8AgAJWNwCAAJA7XA== Date: Wed, 28 Aug 2019 17:31:45 +0000 Message-ID: References: , <6542ac57-6b06-1337-825b-dd1187accd15@vivier.eu> In-Reply-To: <6542ac57-6b06-1337-825b-dd1187accd15@vivier.eu> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=amarkovic@wavecomp.com; x-originating-ip: [82.117.201.26] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 92cb7ad9-89b4-4315-a244-08d72bdd9989 x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(7168020)(4627221)(201703031133081)(201702281549075)(8990200)(5600166)(711020)(4605104)(1401327)(2017052603328)(7193020); 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FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX:1; received-spf: None (protection.outlook.com: wavecomp.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: M1wxF7ErtCDgpdzAHCuedk92uQ8kPqtreBu0rR5W/4QwvnToKsP7OpiP46EMH0y2Plf13U5RoLP6UR++Sjz3Oeps9DeEXt9hNdL+vJo9dxtxAHGjIucJy5ESDt983ZwqfOMdVjdghCHq9DNylzHSsZPg2/s68TRWNQugAQrYBfEjLVQkrSXQFfpUffNGUnYJ7XSVc1kUyBCesFB1iDHwGeQgLNR8U0ce4DMlf15RpXgXP74FyTpUEU2CzgN67X/KPD7Zr28uQ+5TLiuaEhJ+1g6KJNIdrPxgx140b4vFZO20qrWGKqYEeMLWQRx65zLHmHUYCIZTiSsTyPLeXZkFnVuLqacEaIkIpTBnscQPsGQAYHt2lncmiXZAYKH+kvj1v5XqNYJ+74h71wZf+MskU9gOj9xZfZ48dJH4jbI6A/s= Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wavecomp.com X-MS-Exchange-CrossTenant-Network-Message-Id: 92cb7ad9-89b4-4315-a244-08d72bdd9989 X-MS-Exchange-CrossTenant-originalarrivaltime: 28 Aug 2019 17:31:45.8106 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 463607d3-1db3-40a0-8a29-970c56230104 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: /OjRKvk5rVTNJN5MujNu43N19ASZeagY4h2DRbgnaxWT445vEDFMQPf5ReTfOItWA5JY4TPYtlH7I4B+3F3QXg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR2201MB1746 X-detected-operating-system: by eggs.gnu.org: Windows 7 or 8 [fuzzy] X-Received-From: 40.107.78.121 Subject: Re: [Qemu-devel] [EXTERNAL]Re: patch to swap SIGRTMIN + 1 and SIGRTMAX - 1 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , "qemu-trivial@nongnu.org" , "riku.voipio@iki.fi" , "qemu-devel@nongnu.org" , "marlies.ruck@gmail.com" , Shu-Chun Weng Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" > From: Laurent Vivier =0A= > Sent: Wednesday, August 28, 2019 10:51 AM=0A= > To: Josh Kunz; Aleksandar Markovic; milos.stojanovic@rt-rk.com=0A= > Cc: marlies.ruck@gmail.com; qemu-devel@nongnu.org; riku.voipio@iki.fi; > = qemu-trivial@nongnu.org; Peter Maydell; Shu-Chun Weng; Aleksandar Markovic= =0A= > Subject: [EXTERNAL]Re: [Qemu-devel] patch to swap SIGRTMIN + 1 and SIGRTM= AX - 1=0A= > =0A= > Le 26/08/2019 =E0 23:10, Josh Kunz a =E9crit :=0A= > > On Wed, Aug 21, 2019 at 2:28 AM Laurent Vivier > > wrote:=0A= > >=0A= > > Le 19/08/2019 =E0 23:46, Josh Kunz via Qemu-devel a =E9crit :=0A= > > > Hi all,=0A= > > >=0A= > > > I have also experienced issues with SIGRTMIN + 1, and am interest= ed in=0A= > > > moving this patch forwards. Anything I can do here to help? Would= the=0A= > > > maintainers prefer myself or Marli re-submit the patch?=0A= > > >=0A= > > > The Go issue here seems particularly sticky. Even if we update th= e Go=0A= > > > runtime, users may try and run older binaries built with older=0A= > > versions of=0A= > > > Go for quite some time (months? years?). Would it be better to=0A= > > hide this=0A= > > > behind some kind of build-time flag=0A= > > (`--enable-sigrtmin-plus-one-proxy` or=0A= > > > something), so that some users can opt-in, but older binaries=0A= > > still work as=0A= > > > expected?=0A= > > >=0A= > > > Also, here is a link to the original thread this message is in=0A= > > reply to=0A= > > > in-case my mail-client doesn't set up the reply properly:=0A= > > > https://lists.nongnu.org/archive/html/qemu-devel/2019-07/msg01303= .html=0A= > >=0A= > > The problem here is we break something to fix something else.=0A= > >=0A= > > I'm wondering if the series from Aleksandar Markovic, "linux-user:= =0A= > > Support signal passing for targets having more signals than host" [= 1]=0A= > > can fix the problem in a better way?=0A= > >=0A= > >=0A= > > That patch[1] (which I'll refer to as the MUX patch to avoid confusion)= =0A= > > does not directly fix the issue addressed by this patch (re-wiring=0A= > > SIGRTMIN+1), but since it basically implements generic signal=0A= > > multiplexing, it could be re-worked to address this case as well. The= =0A= > > way it handles `si_code` spooks me a little bit. It could easily be=0A= > > broken by a kernel version change, and such a breakage could be hard to= =0A= > > detect or lead to surprising results. Other than that, it looks like a= =0A= > > reasonable implementation.=0A= > >=0A= > > That said, overall, fixing the SIGRTMIN+1 issue using a more-generic=0A= > > signal-multiplexing mechanism doesn't seem *that* much better to me. It= =0A= > > adds a lot of complexity, and only saves a single signal (assuming glib= c=0A= > > doesn't add more reserved signals). The "big win" is additional=0A= > > emulation features, like those introduced in MUX patch (being able to= =0A= > > utilize signals outside of the host range). If having those features in= =0A= > > QEMU warrants the additional complexity, then re-working this patch=0A= > > on-top of that infrastructure seems like a good idea.=0A= > >=0A= > > If the maintainers want to go down that route, then I would be happy to= =0A= > > re-work this patch utilizing the infrastructure from the MUX patch.=0A= > > Unfortunately it will require non-trivial changes, so it may be best to= =0A= > > wait until that patch is merged. I could also provide a patch "on top= =0A= > > of" the MUX patch, if that's desired/more convenient.=0A= > >=0A= > > Just one last note, if you do decide to merge the MUX patch, then it=0A= > > would be best to use SIGRTMAX (instead of SIGRTMAX-1) as the=0A= > > multiplexing signal if possible, to avoid breaking go binaries.=0A= > >=0A= > =0A= > Personally, I prefer a solution that breaks nothing.=0A= > =0A= > Aleksandar, Milos,=0A= > =0A= > do you have an updated version of you series "Support signal passing for= =0A= > targets having more signals than host"?=0A= > =0A= =0A= Milos is unfortunetely working on an entirely different project now, and ca= n't spare enough time to finish the series. I am also busy with other issue= s, even though I would like very much this or equivalent solution to be int= egrated. Alternatively, someone in the team may have time later this year, = but I do not know that yet - perhaps somebody else (Josh) can take over th= e series?=0A= =0A= Sincerely,=0A= Aleksandar=0A= =0A= =0A= > Thanks,=0A= > Laurent=0A= > =