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Thu, 10 Dec 2020 13:48:19 +0000 (UTC) Received: from localhost (unknown [10.36.110.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id 428966064B; Thu, 10 Dec 2020 13:48:10 +0000 (UTC) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 458557fb-3582-4815-a092-145740b29281 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607608105; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ulMUWJhPnu4f0g/wIardZXW7c36v91u4ATkIG/ONjyg=; b=ArTQTcy3FXFs1jzLmExg4fo+1a9AkfgT5G2UqXmmCrl8lHbQyNhfBSQRpRj6E0pMBAGCMl 5hdqmu1bftOnBvh18399JQ8Ns8TrvpEsOBB+dMETawNM5DoDOYWH5sch7U7YLUBlDCC50Q qALAWN7A/cDuPetGh9AEsCUotFOLkGQ= X-MC-Unique: 8PrYjN8sPoKWRVQm0sBUGQ-1 From: marcandre.lureau@redhat.com To: qemu-devel@nongnu.org Cc: philmd@redhat.com, Richard Henderson , Laurent Vivier , Paul Durrant , xen-devel@lists.xenproject.org, Stefan Hajnoczi , Gerd Hoffmann , Stefano Stabellini , Anthony Perard , "Dr. David Alan Gilbert" , qemu-arm@nongnu.org, Paolo Bonzini , Peter Maydell Subject: [PATCH v3 01/13] qemu/atomic: Drop special case for unsupported compiler Date: Thu, 10 Dec 2020 17:47:40 +0400 Message-Id: <20201210134752.780923-2-marcandre.lureau@redhat.com> In-Reply-To: <20201210134752.780923-1-marcandre.lureau@redhat.com> References: <20201210134752.780923-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=marcandre.lureau@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @redhat.com) From: Philippe Mathieu-Daud=C3=A9 Since commit efc6c070aca ("configure: Add a test for the minimum compiler version") the minimum compiler version required for GCC is 4.8, which has the GCC BZ#36793 bug fixed. We can safely remove the special case introduced in commit a281ebc11a6 ("virtio: add missing mb() on notification"). With clang 3.4, __ATOMIC_RELAXED is defined, so the chunk to remove (which is x86-specific), isn't reached either. Signed-off-by: Philippe Mathieu-Daud=C3=A9 Reviewed-by: Marc-Andr=C3=A9 Lureau Reviewed-by: Stefan Hajnoczi --- include/qemu/atomic.h | 17 ----------------- 1 file changed, 17 deletions(-) diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index c1d211a351..8f4b3a80fb 100644 --- a/include/qemu/atomic.h +++ b/include/qemu/atomic.h @@ -241,23 +241,6 @@ =20 #else /* __ATOMIC_RELAXED */ =20 -/* - * We use GCC builtin if it's available, as that can use mfence on - * 32-bit as well, e.g. if built with -march=3Dpentium-m. However, on - * i386 the spec is buggy, and the implementation followed it until - * 4.3 (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D36793). - */ -#if defined(__i386__) || defined(__x86_64__) -#if !QEMU_GNUC_PREREQ(4, 4) -#if defined __x86_64__ -#define smp_mb() ({ asm volatile("mfence" ::: "memory"); (void)0; }) -#else -#define smp_mb() ({ asm volatile("lock; addl $0,0(%%esp) " ::: "memory"= ); (void)0; }) -#endif -#endif -#endif - - #ifdef __alpha__ #define smp_read_barrier_depends() asm volatile("mb":::"memory") #endif --=20 2.29.0