From owner-svn-src-head@FreeBSD.ORG Fri Sep 5 15:53:49 2014 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 746B4D1E; Fri, 5 Sep 2014 15:53:49 +0000 (UTC) Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [IPv6:2001:470:1f11:75::1]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4AD511914; Fri, 5 Sep 2014 15:53:49 +0000 (UTC) Received: from jhbbsd.localnet (unknown [209.249.190.124]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id C99DFB948; Fri, 5 Sep 2014 11:53:47 -0400 (EDT) From: John Baldwin To: Konstantin Belousov Subject: Re: svn commit: r270850 - in head/sys: i386/i386 i386/include i386/isa x86/acpica Date: Fri, 5 Sep 2014 10:44:05 -0400 User-Agent: KMail/1.13.5 (FreeBSD/8.4-CBSD-20140415; KDE/4.5.5; amd64; ; ) References: <201408301748.s7UHmc6H059701@svn.freebsd.org> <3070015.668SIdAzOX@ralph.baldwin.cx> <20140905084305.GN2737@kib.kiev.ua> In-Reply-To: <20140905084305.GN2737@kib.kiev.ua> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <201409051044.05853.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Fri, 05 Sep 2014 11:53:47 -0400 (EDT) Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 05 Sep 2014 15:53:49 -0000 On Friday, September 05, 2014 4:43:05 am Konstantin Belousov wrote: > On Thu, Sep 04, 2014 at 10:50:25PM -0400, John Baldwin wrote: > > On Tuesday, September 02, 2014 06:41:27 PM Konstantin Belousov wrote: > > > On Tue, Sep 02, 2014 at 11:00:57AM -0400, John Baldwin wrote: > > > > I thought about that. I could easily make a parallel array, or perhaps > > > > use a separate 'susppcb' structure that includes a pcb and the savefpu > > > > union and change susppcbs to be an array of those. Which do you prefer? > > > > If we want to move some state out of the PCB on amd64 into this, then a > > > > separate struct for susppcbs might be the sanest. > > > > > > Yes, separate structure seems to be a way forward. > > > > Please see www.freebsd.org/~jhb/patches/susppcb.patch Note that I moved > > fpususpend() out into a C function on amd64 so that resumectx() could still > > operate on just a pcb. This also makes savectx and resumectx more symmetric > > and matches what I ended up doing on i386. This is tested for suspend and > > resume on both i386 and amd64. > > The implementation of fpuresume() in C is definitely an improvement. > > You only moved the fpu context to the susppcb, I think this is good for > now, we will want to move other bits later. > > Do we need to keep pcb layout for KBI compat ? I remember that pcb > size is asserted to properly fit into pcpu area for percpu zones. > But why keep the layout ? I.e. moving all padding bits to the end. I wasn't sure. I thought the padding was there for ABI reasons. If we don't need KBI compat, I would much rather consolidate all the padding at the end. > There is one weird detail, not touched by your patch. Amd64 resume > path calls initializecpu(), while i386 does not. I do not see any > use for the call, the reload of CRX registers by trampoline/resumectx > should already set everything to working state. E.g., enabling XMM > in CR4 after fpu state is restored looks strange. I can test that. > Overall, it looks fine. Do you prefer to have alloc_fpusave() on i386 ? Well, it might be nice to have XSAVE on i386. I'm not sure if Intel has any 32-bit only chips planned that will use AVX or MPX, etc. If they are, then I do think AVX on i386 would be nice to have. Barring XSAVE I think we can just use a static savefpu on i386 for now. We might also consider removing support for 486sx CPUs and requiring an on-CPU FPU for i386. If we do that we might able to use a common fpu.c which would be even nicer. -- John Baldwin