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x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfI5+ySDAJciCK94XIfYWsIJSKfgwK//c/zaYACR9LzMorreF8XFG1Dl/+X7GDeoRlkADXg1MuOxiQxYIpZgw7L5TgYPQOF4XBr6MwcLcgKb6lxiADx8M KP5dOrBlGBoqVf+t3608AJa0mYrixe/MNPxT8fcYN9wp16jtJGT0wfEV0V+rHBald3kRjHF4f8ZGQSI5bsb4jmpKk9uK61NZTPLG2G7k3TTZPcHLTAwZm0WP X-CM-Analysis: v=2.3 cv=WaUilXpX c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=IkcTkHD0fZMA:10 a=VUJBJC2UJ8kA:10 a=VwQbUJbxAAAA:8 a=AD2EB-NJvgJ65bpX8C0A:9 a=QEXdDO2ut3YA:10 a=AjGcO6oz07-iQ99wixmX:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750942AbeECWkJ (ORCPT ); Thu, 3 May 2018 18:40:09 -0400 Received: from mail-qt0-f193.google.com ([209.85.216.193]:45518 "EHLO mail-qt0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750829AbeECWkJ (ORCPT ); Thu, 3 May 2018 18:40:09 -0400 X-Google-Smtp-Source: AB8JxZpwC/dbzbv3DiguOedF1ndr0K3sl6t/LOnYqxFG2v7dTrICbkzY6CLxVxE575Yui8Y1C38uyo5LbEeiTOIP4DU= MIME-Version: 1.0 In-Reply-To: <20180502215107.GA9884@saruman> References: <20180502215107.GA9884@saruman> From: Arnd Bergmann Date: Thu, 3 May 2018 18:40:07 -0400 X-Google-Sender-Auth: zGWEe4vkoxJ789wYH7_oUbrkXyI Message-ID: Subject: Re: Introducing a nanoMIPS port for Linux To: James Hogan Cc: Ralf Baechle , "open list:RALINK MIPS ARCHITECTURE" , linux-arch , Linux Kernel Mailing List , Paul Burton , Matt Redfearn , Marcin Nowakowski , Matthew Fortune Content-Type: text/plain; charset="UTF-8" Sender: linux-arch-owner@vger.kernel.org X-Mailing-List: linux-arch@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, May 2, 2018 at 5:51 PM, James Hogan wrote: > Due to the binary incompatibility between previous MIPS architecture > generations and nanoMIPS, and the significantly revamped compiler ABI, > where for the first time, a single Linux kernel would not be expected to > handle both old and new ABIs, we have decided to also take the > opportunity to modernise the Linux user ABI for nanoMIPS, making as much > use of generic interfaces as possible and modernising the true > architecture specific parts. > > This is similar to what a whole new kernel architecture would be > expected to adopt, but has been done within the existing MIPS > architecture port to allow reuse of the existing MIPS code, most of > which does not depend on these ABI specifics. Details of the proposed > Linux user ABI changes for nanoMIPS can be found here: While I haven't looked at the individual changes, I wonder whether it would be useful to make this new ABI use 64-bit time_t from the start, using the new system calls that Deepa and I have been posting recently. There are still a few things to be worked out: only the first of four sets of syscall patches is merged so far, and we have a couple of areas that will require further ABI changes (sound, sockets, media and maybe a couple of smaller drivers), so it depends on the overall timing. If you would otherwise merge the patches quickly, then it may be better to just follow the existing 32-bit architectures and add the 64-bit entry points when we do it for everyone. Arnd