From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f67.google.com (mail-wm1-f67.google.com [209.85.128.67]) by mx.groups.io with SMTP id smtpd.web10.175.1590616238116998556 for ; Wed, 27 May 2020 14:50:38 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@linuxfoundation.org header.s=google header.b=fgn4LUvc; spf=pass (domain: linuxfoundation.org, ip: 209.85.128.67, mailfrom: richard.purdie@linuxfoundation.org) Received: by mail-wm1-f67.google.com with SMTP id f5so1114069wmh.2 for ; Wed, 27 May 2020 14:50:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=google; h=message-id:subject:from:to:cc:date:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=3yfxXhUCYDa54jyh8hQkvYWjxNF6U5UnayBz1TNh38U=; b=fgn4LUvcoFmTVZqyvSnKefDnSqTwCF+sskq0jDvlwN+x4B/21mE7hM5evceZV6dW/Z klsSl/Em/xRiz1gmpiUZuEwiTQVTT/mwUVcgxJ80Vx7S8HzIOE/rV+LH8RkbDDLJd0o6 oajQrI6wFagM494JXguELryE0zG6op1d/xv9g= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=3yfxXhUCYDa54jyh8hQkvYWjxNF6U5UnayBz1TNh38U=; b=Pg5zVX+IOyMB0ztFI9EVdU8D454EUkf7XmVzRmeV5pGxy+xhk7o2v8rAOxrBY+Ij0B S21oGeBjocafkFLe//HgDseUtdoucR1lTk7jbOjjIa/RPiVQCcuxFvDdK4+aorgyYB6d K45ciTqfrI10HwwzJaGJByCG/rLzmlKvf4l7LhQljBvZt95cgoIZ/whnxSpjlxNn7+SZ F6b6GsC+JaRzcMrrPHiMcUq0yMyEEL98ioIV4UvWIFRKl9kz11uAlgT2VbjCTggRrGoK JoiUSnDB520enN71JwoA8Hp/Mh8KISydo3v5wnAvWIotMTiY04bTWXODgGFkWuyTNSmj 8/hA== X-Gm-Message-State: AOAM530+7eWVHXJdD34b4i+DrNp0Oa8Te7NcLFfPHkgutyGZWKJJLMf8 WPmVTH3soeiqD75D9kx9exvL3g== X-Google-Smtp-Source: ABdhPJx+GczEzu5TR0oUXa+ngD6F1DjFzwzw5upDBAC35jzGmze07aYpOzMhpVRr4z3VbFNRzXjjjw== X-Received: by 2002:a1c:e355:: with SMTP id a82mr157951wmh.1.1590616236595; Wed, 27 May 2020 14:50:36 -0700 (PDT) Return-Path: Received: from hex (5751f4a1.skybroadband.com. [87.81.244.161]) by smtp.gmail.com with ESMTPSA id x186sm4429588wmg.8.2020.05.27.14.50.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2020 14:50:36 -0700 (PDT) Message-ID: Subject: Re: [OE-core] [PATCH] linux-libc-headers: Check for asm/bpf_perf_event.h before multilibbing From: "Richard Purdie" To: Khem Raj Cc: Denys Dmytriyenko , Patches and discussions about the oe-core layer Date: Wed, 27 May 2020 22:50:32 +0100 In-Reply-To: References: <20200527155011.3165976-1-raj.khem@gmail.com> <20200527155957.GK17660@denix.org> <765f3daeb6ce5f28c2d1e258dd303f5707363678.camel@linuxfoundation.org> User-Agent: Evolution 3.36.1-2 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit On Wed, 2020-05-27 at 14:46 -0700, Khem Raj wrote: > On Wed, May 27, 2020 at 2:25 PM Richard Purdie > wrote: > > On Wed, 2020-05-27 at 11:59 -0400, Denys Dmytriyenko wrote: > > > On Wed, May 27, 2020 at 08:50:11AM -0700, Khem Raj wrote: > > > > asm/bpf_perf_event.h does not exist in older kernels e.g. ( 4.1 > > > > ) > > > > this helps in using common header across multiple versions of > > > > kernel > > > > going back > > > > > > This check should have been there from the beginning and for > > > every > > > header > > > file. It's big PITA to sync this list up, especially when dealing > > > with > > > different glibc or kernel than OE-Core, e.g. external toolchains, > > > etc. > > > > > > Any objections to making this check more generic for every entry > > > in > > > the list? > > > > Yes, a strong objection. We don't want to support or encourage > > every > > kernel version out there. > > > > I also don't understand why people need to change the libc-headers > > anyway :( > > building products doesn't mean you are on the latest kernels sadly, > that's just the reality of world > and building userspace against way newer kernel-headers with older > kernel underneath has unintended consequences. Its not supposed to have any consequences, the kernel UAPI is supposed to be backwards compatible. Have you examples where things were broken? > So its always better to use matching UAPIs to the kernel > version to avoid these mismatches This should not be necessary and its actually really bad it it means a totally different userspace for every target :( Cheers, Richard