From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by sourceware.org (Postfix) with ESMTPS id 72DE53858D32 for ; Mon, 8 Apr 2024 13:01:49 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 72DE53858D32 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=ispras.ru Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=ispras.ru ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 72DE53858D32 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=83.149.199.84 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1712581311; cv=none; b=Lob8TJbV7qoOJK5Wj6FQCLXTMfigaUAdATVhy6iA2xmW8jHvB5Ru456FaH+t8IVNrcCJRXg5xra3jHWTKaalqXSgd1dnvZ5QEAZoeGktLt+VYl5WyT0q48mibY1SvFe+ma1qoChG2/UemwkY8Fx0oIrgPBtet2DOO+0EsDg8Zq0= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1712581311; c=relaxed/simple; bh=8S4iDGoDUT6G3OK5Yh6Gjj6rU2sRP8yG6YXIwou+X20=; h=DKIM-Signature:Date:From:To:Subject:Message-ID:MIME-Version; b=MMYPJyhAOOxwYpTz4JIUtvPU7qewj/dJBjC8SYb2SSaeVJSsfTDghoifaWbeAGt/a/JNNXNttxOaEuQvFVH7XUVB8YtFgm1SUGWMlBm3MEfES76hCZcRYI7Eh1TLzeVLedoalESZfvJzmSC7g252srs9sY0MIUUQX1U148HpYtg= ARC-Authentication-Results: i=1; server2.sourceware.org Received: from [10.10.3.121] (unknown [10.10.3.121]) by mail.ispras.ru (Postfix) with ESMTPS id EB54B40762D9; Mon, 8 Apr 2024 13:01:47 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru EB54B40762D9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1712581308; bh=Q0sxZZsx6QF9GlqwQAs6kFZu7h3RAGAwy5C9vymsl3Y=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=n7EXs2PARyMqDXKNSpHbdWRyRRFJ7qCO+awEFNSYHxpAbgi5veQZRVGE9bll5SZpE 46/W/7kAOT5Z9VHbxregL6wbzz5N+lZOhpwL8c3n5SElirgX0y75T7U2JZoKwqyX2B rjvYDj0DgG1Dqw7Ap4HZnWR75P+BINPWZH2t4FTA= Date: Mon, 8 Apr 2024 16:01:47 +0300 (MSK) From: Alexander Monakov To: Florian Weimer cc: Matheus Afonso Martins Moreira via Gcc , Matheus Afonso Martins Moreira Subject: Re: [RFC] Linux system call builtins In-Reply-To: <87h6gcvzsc.fsf@oldenburg.str.redhat.com> Message-ID: <754cbc8d-a1f0-d266-1052-21feda868004@ispras.ru> References: <2d2f1e405361d2b36dd513e3fabd1fe0@gmail.com> <87plv0w10k.fsf@oldenburg.str.redhat.com> <5a5b1c2c-6feb-3bf5-cf08-aa93a1b181b8@ispras.ru> <87h6gcvzsc.fsf@oldenburg.str.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Mon, 8 Apr 2024, Florian Weimer wrote: > * Alexander Monakov: > > >> There is quite a bit of variance in how the kernel is entered. On > >> x86-64, one once popular mechanism is longer present in widely-used > >> kernels. > > > > I assume you're implicitly referencing the vsyscall mechanism, but on > > amd64 it's not useful to *enter the kernel*, right? It was useful for > > obtaining the result of certain syscalls without actually entering > > the kernel, like with vdso. > > The implementation performed a standard system call if a pure userspace > implementation wasn't possible. It wasn't intended as a general-purpose > way to enter the kernel (although it could be used as such, hence the > desire to remove it in some cases). I guess you meant it was "popular" only for the specific syscalls it provided acceleration for. I'm not sure how that is relevant to the current discussion. Alexander