From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f178.google.com (mail-qc0-f178.google.com [209.85.216.178]) by kanga.kvack.org (Postfix) with ESMTP id 45D4F6B0031 for ; Tue, 28 Jan 2014 16:28:43 -0500 (EST) Received: by mail-qc0-f178.google.com with SMTP id m20so1513057qcx.9 for ; Tue, 28 Jan 2014 13:28:43 -0800 (PST) Received: from mail-qc0-x230.google.com (mail-qc0-x230.google.com [2607:f8b0:400d:c01::230]) by mx.google.com with ESMTPS id g48si12323135qge.133.2014.01.28.13.28.41 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 28 Jan 2014 13:28:42 -0800 (PST) Received: by mail-qc0-f176.google.com with SMTP id e16so1464659qcx.21 for ; Tue, 28 Jan 2014 13:28:41 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <52E81BB3.6060306@linaro.org> References: <52E709C0.1050006@linaro.org> <52E7298D.5020001@zytor.com> <52E80B85.8020302@linaro.org> <52E814FF.6060403@zytor.com> <52E819F0.6040806@linaro.org> <52E81BB3.6060306@linaro.org> From: Kay Sievers Date: Tue, 28 Jan 2014 22:28:21 +0100 Message-ID: Subject: Re: [RFC] shmgetfd idea Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: John Stultz Cc: "H. Peter Anvin" , "linux-mm@kvack.org" , Greg KH , Android Kernel Team , Andrew Morton , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Michel Lespinasse , Johannes Weiner , Neil Brown , Andrea Arcangeli , Takahiro Akashi , Minchan Kim , Lennart Poettering On Tue, Jan 28, 2014 at 10:05 PM, John Stultz wrote: > On 01/28/2014 01:01 PM, Kay Sievers wrote: >> On Tue, Jan 28, 2014 at 9:58 PM, John Stultz wrote: >>> On 01/28/2014 12:37 PM, H. Peter Anvin wrote: >>>> On 01/28/2014 11:56 AM, John Stultz wrote: >>>>> Thanks for reminding me about O_TMPFILE.. I have it on my list to look >>>>> into how it could be used. >>>>> >>>>> As for the O_TMPFILE only tmpfs option, it seems maybe a little clunky >>>>> to me, but possible. If others think this would be preferred over a new >>>>> syscall, I'll dig in deeper. >>>>> >>>> What is clunky about it? It reuses an existing interface and still >>>> points to the specific tmpfs instance that should be populated. >>> It would require new mount point convention that userland would have to >>> standardize. To me (and admittedly its a taste thing), a new >>> O_TMPFILE-only tmpfs mount point seems to be to be a bigger interface >>> change from an application writers perspective then a new syscall. >>> >>> But maybe I'm misunderstanding your suggestion? >> General purpose Linux has /dev/shm/ for that already, which will not >> go away anytime soon.. > > Right, though making /dev/shm/ O_TMPFILE only would likely break things, no? Right, general purpose Linux could not mount with that option without expecting major breakage, see: man shm_overview. But a custom OS could just define that, I guess. The current /dev/shm/ semantics and the shm apis in general are a kind of a broken idea from the very beginning. Kay -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org