From c1f64a58003fd2efaa725a857e269a15f765791a Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 27 May 2008 09:47:13 -0700 Subject: x86: MMIO and gcc re-ordering issue On Tue, 27 May 2008, Linus Torvalds wrote: > > Expecting people to fix up all drivers is simply not going to happen. And > serializing things shouldn't be *that* expensive. People who cannot take > the expense can continue to use the magic __raw_writel() etc stuff. Of course, for non-x86, you kind of have to expect drivers to be well-behaved, so non-x86 can probably avoid this simply because there are less relevant drivers involved. Here's a UNTESTED patch for x86 that may or may not compile and work, and which serializes (on a compiler level) the IO accesses against regular memory accesses. __read[bwlq]()/__write[bwlq]() are not serialized with a :"memory" barrier, although since they still use "asm volatile" I suspect that i practice they are probably serial too. Did not look very closely at any generated code (only did a trivial test to see that the code looks *roughly* correct). Signed-off-by: Ingo Molnar --- include/asm-x86/io_32.h | 49 ------------------------------------------------- 1 file changed, 49 deletions(-) (limited to 'include/asm-x86/io_32.h') diff --git a/include/asm-x86/io_32.h b/include/asm-x86/io_32.h index 049e81e797a0..d71be8df9797 100644 --- a/include/asm-x86/io_32.h +++ b/include/asm-x86/io_32.h @@ -149,55 +149,6 @@ extern void __iomem *fix_ioremap(unsigned idx, unsigned long phys); #define virt_to_bus virt_to_phys #define bus_to_virt phys_to_virt -/* - * readX/writeX() are used to access memory mapped devices. On some - * architectures the memory mapped IO stuff needs to be accessed - * differently. On the x86 architecture, we just read/write the - * memory location directly. - */ - -static inline unsigned char readb(const volatile void __iomem *addr) -{ - return *(volatile unsigned char __force *)addr; -} - -static inline unsigned short readw(const volatile void __iomem *addr) -{ - return *(volatile unsigned short __force *)addr; -} - -static inline unsigned int readl(const volatile void __iomem *addr) -{ - return *(volatile unsigned int __force *) addr; -} - -#define readb_relaxed(addr) readb(addr) -#define readw_relaxed(addr) readw(addr) -#define readl_relaxed(addr) readl(addr) -#define __raw_readb readb -#define __raw_readw readw -#define __raw_readl readl - -static inline void writeb(unsigned char b, volatile void __iomem *addr) -{ - *(volatile unsigned char __force *)addr = b; -} - -static inline void writew(unsigned short b, volatile void __iomem *addr) -{ - *(volatile unsigned short __force *)addr = b; -} - -static inline void writel(unsigned int b, volatile void __iomem *addr) -{ - *(volatile unsigned int __force *)addr = b; -} -#define __raw_writeb writeb -#define __raw_writew writew -#define __raw_writel writel - -#define mmiowb() - static inline void memset_io(volatile void __iomem *addr, unsigned char val, int count) { -- cgit v1.2.3 From 4583ed514ea9ac844a6eb02d33120beaedf6837f Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 25 Jun 2008 00:19:03 -0400 Subject: x86, 64-bit: unify early_ioremap The 32-bit early_ioremap will work equally well for 64-bit, so just use it. Signed-off-by: Jeremy Fitzhardinge Cc: xen-devel Cc: Stephen Tweedie Cc: Eduardo Habkost Cc: Mark McLoughlin Signed-off-by: Ingo Molnar --- include/asm-x86/io_32.h | 12 ------------ 1 file changed, 12 deletions(-) (limited to 'include/asm-x86/io_32.h') diff --git a/include/asm-x86/io_32.h b/include/asm-x86/io_32.h index d71be8df9797..4df44ed54077 100644 --- a/include/asm-x86/io_32.h +++ b/include/asm-x86/io_32.h @@ -121,18 +121,6 @@ static inline void __iomem *ioremap(resource_size_t offset, unsigned long size) extern void iounmap(volatile void __iomem *addr); -/* - * early_ioremap() and early_iounmap() are for temporary early boot-time - * mappings, before the real ioremap() is functional. - * A boot-time mapping is currently limited to at most 16 pages. - */ -extern void early_ioremap_init(void); -extern void early_ioremap_clear(void); -extern void early_ioremap_reset(void); -extern void *early_ioremap(unsigned long offset, unsigned long size); -extern void early_iounmap(void *addr, unsigned long size); -extern void __iomem *fix_ioremap(unsigned idx, unsigned long phys); - /* * ISA I/O bus memory addresses are 1:1 with the physical address. */ -- cgit v1.2.3