From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id F064F385841A for ; Mon, 13 Sep 2021 13:44:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org F064F385841A Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-499-pN2fJrZiNQmhcyKxilfGVw-1; Mon, 13 Sep 2021 09:44:13 -0400 X-MC-Unique: pN2fJrZiNQmhcyKxilfGVw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 69F1A9126D; Mon, 13 Sep 2021 13:44:12 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.195.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 452EB6A8EE; Mon, 13 Sep 2021 13:44:11 +0000 (UTC) From: Florian Weimer To: Vincent Chen Cc: libc-alpha@sourceware.org, palmer@dabbelt.com, andrew@sifive.com Subject: Re: [RFC patch 2/5] RISC-V: Reserve about 5K space in mcontext_t to support future ISA expansion. References: <1631497278-29829-1-git-send-email-vincent.chen@sifive.com> <1631497278-29829-3-git-send-email-vincent.chen@sifive.com> Date: Mon, 13 Sep 2021 15:44:09 +0200 In-Reply-To: <1631497278-29829-3-git-send-email-vincent.chen@sifive.com> (Vincent Chen's message of "Mon, 13 Sep 2021 09:41:15 +0800") Message-ID: <871r5sd1zq.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Sep 2021 13:44:18 -0000 * Vincent Chen: > Following the changes of struct sigcontext in Linux to reserve about 5K space > to support future ISA expansion. > --- > sysdeps/unix/sysv/linux/riscv/sys/ucontext.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/sysdeps/unix/sysv/linux/riscv/sys/ucontext.h b/sysdeps/unix/sysv/linux/riscv/sys/ucontext.h > index cfafa44..80caf07 100644 > --- a/sysdeps/unix/sysv/linux/riscv/sys/ucontext.h > +++ b/sysdeps/unix/sysv/linux/riscv/sys/ucontext.h > @@ -82,6 +82,8 @@ typedef struct mcontext_t > { > __riscv_mc_gp_state __gregs; > union __riscv_mc_fp_state __fpregs; > + /* 5K + 256 reserved for vector state and future expansion. */ > + unsigned char __reserved[5376] __attribute__ ((__aligned__ (16))); > } mcontext_t; This changes the size of struct ucontext_t, which is an ABI break (getcontext callers are supposed to provide their own object). This shouldn't be necessary if the additional vector registers are caller-saved. Thanks, Florian