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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D6856C48260 for ; Tue, 13 Feb 2024 05:24:18 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=U8AnevQX; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4TYqWP1rYTz3dVS for ; Tue, 13 Feb 2024 16:24:17 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=U8AnevQX; dkim-atps=neutral Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4TYqVZ1lhBz3blb for ; Tue, 13 Feb 2024 16:23:34 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1707801814; bh=+E1HErWM5xFmNg1BqO70tvM6TCMQeHvbFhSJJ5P6LZQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=U8AnevQX52O+tdAKYXmbDnbXbdb6QNeA7oGOe6P/LhY/InUZUVRrMYnnr20Nel3AZ /IucdFtczzftJ0BoXnMvUe08ym8psqtOGFLcIyS96vaHGpIKS0hgFIecgwRNSHVnaA kCL/YcOhibmlf2djWX/wl2kHa2U86bQCa9mxWQkakmkhtGsnnsEmMyVIRxXTkUaV/g 6+rI0xu+3pEyohZfi3hNtM88Io7Rq1gPhH/hgV6Y1qUhsrEDITKkWleqftkGG1LhRj GCU8ZvVL+pNCPA6Yto33oyb6U/chOUl5NstQSVxTj0FV0HIwCRHbsgjzy0ApcOxY8T wWY/CoZlEPdEw== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4TYqVY4lHGz4wcQ; Tue, 13 Feb 2024 16:23:33 +1100 (AEDT) From: Michael Ellerman To: Timothy Pearson , Segher Boessenkool Subject: Re: [PATCH] powerpc: Add gpr1 and fpu save/restore functions In-Reply-To: <325865766.14859393.1707762675351.JavaMail.zimbra@raptorengineeringinc.com> References: <995988479.14839534.1707756078600.JavaMail.zimbra@raptorengineeringinc.com> <20240212170207.GW19790@gate.crashing.org> <1251499652.14843228.1707757778984.JavaMail.zimbra@raptorengineeringinc.com> <20240212173043.GX19790@gate.crashing.org> <572013249.14851324.1707759979044.JavaMail.zimbra@raptorengineeringinc.com> <20240212175906.GY19790@gate.crashing.org> <1119220086.14855806.1707761223318.JavaMail.zimbra@raptorengineeringinc.com> <20240212182322.GZ19790@gate.crashing.org> <325865766.14859393.1707762675351.JavaMail.zimbra@raptorengineeringinc.com> Date: Tue, 13 Feb 2024 16:23:30 +1100 Message-ID: <87r0hh6ip9.fsf@mail.lhotse> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Timothy Pearson writes: > ----- Original Message ----- >> From: "Segher Boessenkool" >> To: "Timothy Pearson" >> Cc: "linuxppc-dev" >> Sent: Monday, February 12, 2024 12:23:22 PM >> Subject: Re: [PATCH] powerpc: Add gpr1 and fpu save/restore functions > >> On Mon, Feb 12, 2024 at 12:07:03PM -0600, Timothy Pearson wrote: >>> > I have done it for *all* architectures some ten years ago. Never found >>> > any problem. >>> >>> That makes sense, what I mean by invasive is that we'd need buy-in from the >>> other >>> maintainers across all of the affected architectures. Is that likely to occur? >> >> I don't know. Here is my PowerPC-specific patch, it's a bit older, it >> might not apply cleanly anymore, the changes needed should be obvious >> though: >> >> >> === 8< === >> commit f16dfa5257eb14549ce22243fb2b465615085134 >> Author: Segher Boessenkool >> Date: Sat May 3 03:48:06 2008 +0200 >> >> powerpc: Link vmlinux against libgcc.a >> >> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile >> index b7212b619c52..0a2fac6ffc1c 100644 >> --- a/arch/powerpc/Makefile >> +++ b/arch/powerpc/Makefile >> @@ -158,6 +158,9 @@ core-y += arch/powerpc/kernel/ >> core-$(CONFIG_XMON) += arch/powerpc/xmon/ >> core-$(CONFIG_KVM) += arch/powerpc/kvm/ >> >> +LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name) >> +libs-y += $(LIBGCC) >> + >> drivers-$(CONFIG_OPROFILE) += arch/powerpc/oprofile/ >> >> # Default to zImage, override when needed >> === 8< === > > OK. PowerPC maintainers, how would you prefer to handle this? I'll take the patch to add the functions for now. We can look into linking against libgcc as a future cleanup. >>> > There are better options than -Os, fwiw. Some --param's give smaller >>> > *and* faster kernels. What exactly is best is heavily arch-dependent >>> > though (as well as dependent on the application code, the kernel code in >>> > this case) :-( >>> >>> I've been through this a few times, and -Os is the only option that makes >>> things (just barely) fit unfortunately. >> >> -O2 with appropriate inlining tuning beats -Os every day of the week, >> in my experience. > > On 6.6 it's 24MiB vs 40MiB, O2 vs. Os. :( What compiler/config etc. are you using for that? I see almost no difference, though the defconfig (which uses -O2) is actually smaller: $ ls -l vmlinux.Os vmlinux.defconfig -rwxr-xr-x. 1 michael michael 49936640 Feb 13 16:11 vmlinux.defconfig* -rwxr-xr-x. 1 michael michael 50108392 Feb 13 16:14 vmlinux.Os* cheers