From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id EC7321F4B5 for ; Tue, 12 Nov 2019 15:26:28 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:to:references:from:subject:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; q=dns; s=default; b=p+diCrVq9Y5hh2MP B+22KxMZb3irfwDdO63TUJ5xBYWrCBmakhn2+8tMw2N3RqYaVU0nMfN7YtxtTukY XHMzMrrrt9HQcJ2h7T92b112jNyXMdmvuDfZtEew1X1j0ay4JVBrfERCsYBZCnYs w1nRXcxb40QCVGgCkwUYSWskifM= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:to:references:from:subject:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; s=default; bh=41phYCXQ/6Ku/pJjIya8R9 DQz6E=; b=WpuzxiG8a1zM8bXZV6VXeSMhad1b0uMXtdodPJfNZcIkxlWCnneRiX 5gvMIoL4IPgS5diG/prrjaJ3RZzT1rtWzWuZu6qT+TlymxgIKUIlG28Xd8pb16VR fEvCNKCNNlGx45t5zayDbe3HP4ff3FY+dRO/nxYEWtbmguX/vmsAA= Received: (qmail 19959 invoked by alias); 12 Nov 2019 15:26:26 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 19951 invoked by uid 89); 12 Nov 2019 15:26:26 -0000 Authentication-Results: sourceware.org; auth=none X-HELO: mail-qk1-f194.google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=to:references:from:openpgp:autocrypt:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=dFoeuuXzcwCTeer4wWhon66XYXE6+jws7HJUgY6zYEk=; b=VriTqQflG4H9G4Hwfon2ZeUGniaqDFhnL96Y0CO0nsTAK+j13TI0LfrnUYs9cilX8w WdVpj5URv6f7kBNh4LPL/UaIkHvI9R0kkT64Ye0cKKXDhmri2C30LD+JOr6F3Ep9hT1X ZueUEbSmHjS7gyOac03zwHmtTKDcBr/uhs38loAV+h9+1/eXTTiBP9y+m3t4S50uNlXu K48/try0W5ID4Ps21ZyYNsTcA4Ry7jofosEfub7MT+wENB/NtM0W1NVL0FIlnXRpSxit 1+3KvwEDi0ZNA34av6FJdqshMUPPSR0l12roeTV4BIk4BlwQ6etEjrt5aquYfVH1AUcf dDnQ== To: libc-alpha@sourceware.org References: <20191112133953.0c3594ed@jawa> From: Adhemerval Zanella Openpgp: preference=signencrypt Subject: Re: Question regarding minimal supported Linux kernel headers (now it is 3.2.0) Message-ID: Date: Tue, 12 Nov 2019 12:26:17 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit On 12/11/2019 11:13, Joseph Myers wrote: > On Tue, 12 Nov 2019, Lukasz Majewski wrote: > >> The pselect6 conversion has been postponed on purpose as microblaze >> port gained support for pselect6 from Linux kernel 3.15. Between 3.2 >> (minimal supported glibc Linux headers) and 3.15 this syscall is >> emulated and hence the generic code is convoluted. >> >> For the above reason the conversion of pselect6 has been postponed until >> the minimal glibc's Linux headers are bumped to the version after 3.15. >> >> Dear community - when the minimal glibc version may be increased? >> >> Are there any guidelines when the minimal version shall be increased >> (like once per X glibc releases) ? > > For pselect6, I suggest a preparatory change increasing the minimum > version for microblaze only and removing the racy emulation code from > glibc citing bug 9813, which could then be marked as FIXED with > appropriate milestone set once the emulation code has been completely > removed. (misc/pselect.c would change to an ENOSYS stub complete with > stub_warning call.) > Another possibility, to avoid pessimization and make microblaze an outlier regarding minimum kernel support (although I think we already have alpha in this state) would be: 1. Move generic pselect as microblaze linux specific implementation. 2. Clean-up linux implementation to just use pselect6. 3. Set generic as default ENOSYS/stub and set bug 9813 fixed. 4. Base microblaze implementation on Linux generic and use fallback only if it returns ENOSYS. 5. Remove __ASSUME_PSELECT6. 6. Implement __pselect6_time64 as __ppoll_time64. The microblaze will just call the __pselec6 redefined as another symbol and use fallback just if it returns ENOSYS. The generic __pselec6 will use the usual path: __pselec6_time64 then __pselec6 if ENOSYS. This is a performance hit on microblaze from kernel 3.2 to 3.15, but I think if pselect is indeed required, it is also expected that an updated kernel would be used. Something like https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/azanella/pselect-time64