From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0EB75C54E4A for ; Tue, 12 May 2020 08:53:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E5705206B7 for ; Tue, 12 May 2020 08:53:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729265AbgELIxw (ORCPT ); Tue, 12 May 2020 04:53:52 -0400 Received: from mx2.suse.de ([195.135.220.15]:40914 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726067AbgELIxv (ORCPT ); Tue, 12 May 2020 04:53:51 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 05E73ABC7; Tue, 12 May 2020 08:53:52 +0000 (UTC) From: Andreas Schwab To: Linus Torvalds Cc: Palmer Dabbelt , linux-riscv@lists.infradead.org, Linux Kernel Mailing List Subject: Re: [GIT PULL] RISC-V Fixes for 5.7-rc5 References: X-Yow: Two LITTLE black dots and one BIG black dot...nice 'n' FLUFFY!! Date: Tue, 12 May 2020 10:53:49 +0200 In-Reply-To: (Linus Torvalds's message of "Mon, 11 May 2020 12:04:09 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.91 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mai 11 2020, Linus Torvalds wrote: > Why is glibc doing it in the first place? Is it some historical thing > that is simply irrelevant on RISC-V simply because RISC-V doesn't have > that kind of history, perhaps? It is completely generic. Even new architectures become old over time and accumulate cruft. The idea is that if you configure glibc with --enable-kernel=VERSION, it assumes that all syscalls from kernel VERSION are guaranteed to exist, and drops the fallbacks for those syscalls, or uses them in the first place (if no useful fallback existed). From time to time the absolute minimum supported kernel version is increased (this happend the last time in 2017, when x86 and x86_64 moved the mininum from 2.6.32 to 3.2, after all other architectures did that step in 2016), which allows removing the fallback code that becomes obsolete. Andreas. -- Andreas Schwab, SUSE Labs, schwab@suse.de GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."