From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 0/3] System call table generation support Date: Thu, 20 Sep 2018 23:09:41 -0700 Message-ID: <20180921060941.GB13865@infradead.org> References: <1536914314-5026-1-git-send-email-firoz.khan@linaro.org> <20180917171720.wda5qrl7hyyacmwl@pburton-laptop> <20180920204833.gpypjjxcmxjupls6@pburton-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20180920204833.gpypjjxcmxjupls6@pburton-laptop> Sender: linux-kernel-owner@vger.kernel.org To: Paul Burton Cc: Arnd Bergmann , Firoz Khan , Hauke Mehrtens , =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= , "open list:RALINK MIPS ARCHITECTURE" , Ralf Baechle , James Hogan , gregkh , Philippe Ombredanne , Thomas Gleixner , Kate Stewart , y2038 Mailman List , Linux Kernel Mailing List , linux-arch , Deepa Dinamani , Marcin Juszkiewicz List-Id: linux-arch.vger.kernel.org On Thu, Sep 20, 2018 at 08:48:37PM +0000, Paul Burton wrote: > > Speaking of nanoMIPS, what is your plan for the syscall ABI there? > > I can see two ways of approaching it: > > > > a) keep all the MIPSisms in the data structures, and just use a subset of > > o32 that drops all the obsolete entry points > > b) start over and stay as close as possible to the generic ABI, using the > > asm-generic versions of both the syscall table and the uapi header > > files instead of the traditional version. > > We've taken option b in our current downstream kernel & that's what I > hope we'll get upstream too. There's no expectation that we'll ever need > to mix pre-nanoMIPS & nanoMIPS ISAs or their associated ABIs across the > kernel/user boundary so it's felt like a great opportunity to clean up & > standardise. > > Getting nanoMIPS/p32 support submitted upstream is on my to-do list, but > there's a bunch of prep work to get in first & of course that to-do list > is forever growing. Hopefully in the next couple of cycles. p32 is just the ABI name for nanoMIPS or yet another MIPS ABI? Either way, І think if there is yet another ABI even on an existing port we should always aim for the asm-generic syscall table indeed. Especially for mips where o32 has a rather awkward ABI only explained by odd decisions more than 20 years ago. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:47368 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388944AbeIUL5O (ORCPT ); Fri, 21 Sep 2018 07:57:14 -0400 Date: Thu, 20 Sep 2018 23:09:41 -0700 From: Christoph Hellwig Subject: Re: [PATCH 0/3] System call table generation support Message-ID: <20180921060941.GB13865@infradead.org> References: <1536914314-5026-1-git-send-email-firoz.khan@linaro.org> <20180917171720.wda5qrl7hyyacmwl@pburton-laptop> <20180920204833.gpypjjxcmxjupls6@pburton-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180920204833.gpypjjxcmxjupls6@pburton-laptop> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Paul Burton Cc: Arnd Bergmann , Firoz Khan , Hauke Mehrtens , =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= , "open list:RALINK MIPS ARCHITECTURE" , Ralf Baechle , James Hogan , gregkh , Philippe Ombredanne , Thomas Gleixner , Kate Stewart , y2038 Mailman List , Linux Kernel Mailing List , linux-arch , Deepa Dinamani , Marcin Juszkiewicz Message-ID: <20180921060941.jHZcldQTzxkQdPIwQWqN3QnsOdh_6w9EM4zNaMzvCrw@z> On Thu, Sep 20, 2018 at 08:48:37PM +0000, Paul Burton wrote: > > Speaking of nanoMIPS, what is your plan for the syscall ABI there? > > I can see two ways of approaching it: > > > > a) keep all the MIPSisms in the data structures, and just use a subset of > > o32 that drops all the obsolete entry points > > b) start over and stay as close as possible to the generic ABI, using the > > asm-generic versions of both the syscall table and the uapi header > > files instead of the traditional version. > > We've taken option b in our current downstream kernel & that's what I > hope we'll get upstream too. There's no expectation that we'll ever need > to mix pre-nanoMIPS & nanoMIPS ISAs or their associated ABIs across the > kernel/user boundary so it's felt like a great opportunity to clean up & > standardise. > > Getting nanoMIPS/p32 support submitted upstream is on my to-do list, but > there's a bunch of prep work to get in first & of course that to-do list > is forever growing. Hopefully in the next couple of cycles. p32 is just the ABI name for nanoMIPS or yet another MIPS ABI? Either way, І think if there is yet another ABI even on an existing port we should always aim for the asm-generic syscall table indeed. Especially for mips where o32 has a rather awkward ABI only explained by odd decisions more than 20 years ago.