Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933641AbXLNNe2 (ORCPT ); Fri, 14 Dec 2007 08:34:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759477AbXLNNeT (ORCPT ); Fri, 14 Dec 2007 08:34:19 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:48841 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762882AbXLNNeS (ORCPT ); Fri, 14 Dec 2007 08:34:18 -0500 Date: Fri, 14 Dec 2007 14:33:38 +0100 From: Ingo Molnar To: Andi Kleen Cc: Pavel Machek , Alan Cox , David Newall , "H. Peter Anvin" , Krzysztof Halasa , Rene Herman , "David P. Reed" , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops Message-ID: <20071214133338.GA24895@elte.hu> References: <20071209212513.GC24284@elf.ucw.cz> <475CBDD7.5050602@keyaccess.nl> <475DE37F.20706@davidnewall.com> <475DE6F4.80702@zytor.com> <475DEB23.1000304@davidnewall.com> <20071211131413.1079be59@the-village.bc.nu> <20071211133249.GA16750@one.firstfloor.org> <20071211134725.GB17992@elf.ucw.cz> <20071211135020.GB16750@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071211135020.GB16750@one.firstfloor.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4837 Lines: 144 * Andi Kleen wrote: > > Why is TSC significant? udelay() based on bogomips seems to be good > > enough...? > > Maybe I'm not sure how accurate it really is on non TSC system. On the > other hand it is unclear that the port 80 IO is always the same time > so it's probably ok to vary a bit. So most likely going to udelay() > unconditionally is fine. yep, agreed, and have queued up the patch below. I've killed the misc_*.c outb_p() uses because they happen before there's an udelay() available - but that should be perfectly fine anyway: i dont remember any video hardware that needed pauses for cursor updates, i think those _p()'s just came in accidentally. (there's hardware that needed _p() for other aspects of video such as mode switching - but cursor updates ...) Ingo ------------------> Subject: x86: fix in/out_p delays From: Ingo Molnar Debugged by David P. Reed . Do not use port 0x80, it can cause crashes, see: http://bugzilla.kernel.org/show_bug.cgi?id=6307 http://bugzilla.kernel.org/show_bug.cgi?id=9511 instead of just removing _p postfixes en masse, lets just first remove the 0x80 port usage, then remove any unnecessary _p io ops gradually. It's more debuggable this way. Signed-off-by: Ingo Molnar --- arch/x86/boot/compressed/misc_32.c | 8 ++++---- arch/x86/boot/compressed/misc_64.c | 8 ++++---- arch/x86/kernel/quirks.c | 10 ++++++++++ include/asm-x86/io_32.h | 5 +---- include/asm-x86/io_64.h | 5 +---- 5 files changed, 20 insertions(+), 16 deletions(-) Index: linux-x86.q/arch/x86/boot/compressed/misc_32.c =================================================================== --- linux-x86.q.orig/arch/x86/boot/compressed/misc_32.c +++ linux-x86.q/arch/x86/boot/compressed/misc_32.c @@ -276,10 +276,10 @@ static void putstr(const char *s) RM_SCREEN_INFO.orig_y = y; pos = (x + cols * y) * 2; /* Update cursor position */ - outb_p(14, vidport); - outb_p(0xff & (pos >> 9), vidport+1); - outb_p(15, vidport); - outb_p(0xff & (pos >> 1), vidport+1); + outb(14, vidport); + outb(0xff & (pos >> 9), vidport+1); + outb(15, vidport); + outb(0xff & (pos >> 1), vidport+1); } static void* memset(void* s, int c, unsigned n) Index: linux-x86.q/arch/x86/boot/compressed/misc_64.c =================================================================== --- linux-x86.q.orig/arch/x86/boot/compressed/misc_64.c +++ linux-x86.q/arch/x86/boot/compressed/misc_64.c @@ -275,10 +275,10 @@ static void putstr(const char *s) RM_SCREEN_INFO.orig_y = y; pos = (x + cols * y) * 2; /* Update cursor position */ - outb_p(14, vidport); - outb_p(0xff & (pos >> 9), vidport+1); - outb_p(15, vidport); - outb_p(0xff & (pos >> 1), vidport+1); + outb(14, vidport); + outb(0xff & (pos >> 9), vidport+1); + outb(15, vidport); + outb(0xff & (pos >> 1), vidport+1); } static void* memset(void* s, int c, unsigned n) Index: linux-x86.q/arch/x86/kernel/quirks.c =================================================================== --- linux-x86.q.orig/arch/x86/kernel/quirks.c +++ linux-x86.q/arch/x86/kernel/quirks.c @@ -3,9 +3,19 @@ */ #include #include +#include #include +/* + * Some legacy devices need delays for IN/OUT sequences. Most are + * probably not needed but it's the safest to just do this short delay: + */ +void native_io_delay(void) +{ + udelay(1); +} + #if defined(CONFIG_X86_IO_APIC) && defined(CONFIG_SMP) && defined(CONFIG_PCI) static void __devinit quirk_intel_irqbalance(struct pci_dev *dev) Index: linux-x86.q/include/asm-x86/io_32.h =================================================================== --- linux-x86.q.orig/include/asm-x86/io_32.h +++ linux-x86.q/include/asm-x86/io_32.h @@ -250,10 +250,7 @@ static inline void flush_write_buffers(v #endif /* __KERNEL__ */ -static inline void native_io_delay(void) -{ - asm volatile("outb %%al,$0x80" : : : "memory"); -} +extern void native_io_delay(void); #if defined(CONFIG_PARAVIRT) #include Index: linux-x86.q/include/asm-x86/io_64.h =================================================================== --- linux-x86.q.orig/include/asm-x86/io_64.h +++ linux-x86.q/include/asm-x86/io_64.h @@ -35,10 +35,7 @@ * - Arnaldo Carvalho de Melo */ -static inline void native_io_delay(void) -{ - asm volatile("outb %%al,$0x80" : : : "memory"); -} +extern void native_io_delay(void); #if defined(CONFIG_PARAVIRT) #include -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/