From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 44293 invoked by alias); 11 Jun 2018 20:04:38 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 44263 invoked by uid 89); 11 Jun 2018 20:04:37 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-6.9 required=5.0 tests=BAYES_00,GIT_PATCH_2,SPF_PASS autolearn=ham version=3.3.2 spammy= X-HELO: mail.efficios.com DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 07DF11BCA1B Date: Mon, 11 Jun 2018 20:04:00 -0000 From: Mathieu Desnoyers To: Florian Weimer Cc: Carlos O'Donell , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Thomas Gleixner , linux-kernel , libc-alpha Message-ID: <305409897.10888.1528747473727.JavaMail.zimbra@efficios.com> In-Reply-To: <31fc101a-295b-067b-1a82-7e9e509fc92f@redhat.com> References: <1084280721.10859.1528746558696.JavaMail.zimbra@efficios.com> <31fc101a-295b-067b-1a82-7e9e509fc92f@redhat.com> Subject: Re: Restartable Sequences system call merged into Linux MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-06/txt/msg00211.txt.bz2 ----- On Jun 11, 2018, at 3:55 PM, Florian Weimer fweimer@redhat.com wrote: > On 06/11/2018 09:49 PM, Mathieu Desnoyers wrote: >> It should be noted that there can be only one rseq TLS area registered per >> thread, >> which can then be used by many libraries and by the executable, so this is a >> process-wide (per-thread) resource that we need to manage carefully. > > Is it possible to resize the area after thread creation, perhaps even > from other threads? I'm not sure why we would want to resize it. The per-thread area is fixed-size. Its layout is here: include/uapi/linux/rseq.h: struct rseq The ABI is designed so that all users (program and libraries) can interact through this per-thread TLS area. > > If there is only one contiguous area, this generally means there needs > to be linker support, similar to what we have for initial-exec TLS today. Not entirely sure what you imply by "one contiguous area". All we need is a single fixed-size TLS area for each thread. Thanks, Mathieu > > Thanks, > Florian -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com