Messages in this thread Patch in this message | | | Date | 15 Jan 2004 10:22:19 +0100 | Date | Thu, 15 Jan 2004 10:22:19 +0100 | From | Andi Kleen <> | Subject | Re: [PATCH] Add CONFIG for -mregparm=3 |
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On Thu, Jan 15, 2004 at 11:40:11AM +1100, Rusty Russell wrote: > On Wed, 14 Jan 2004 10:06:03 +0100 > Andi Kleen <ak@muc.de> wrote: > > I didn't make it the default because it will break all binary only > > modules (although they can be fixed by adding a wrapper that > > calls them with "asmlinkage"). Actually it may be a good idea to > > make this default with 2.7.1 or somesuch. > > Who cares. Anyway, if kept as a config option, this should probably be > added to MODULE_ARCH_VERMAGIC in include/asm-i386/module.h.
Ok. Good point.
On second thought I'm actually not opposed to make it the default, but Linus/Andrew have to decide if they want this. It certainly would be a good strategy longer term (even though it would eliminate some of the advantages x86-64 currently enjoys over i386 ;-)
New patch appended.
-Andi
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Add CONFIG_REGPARM option to enable compilation with -mregparm=3. This shrinks the kernel .text considerably.
This could be made default later when it has been more tested.
diff -u linux-34/arch/i386/Kconfig-o linux-34/arch/i386/Kconfig --- linux-34/arch/i386/Kconfig-o 2004-01-09 09:27:09.000000000 +0100 +++ linux-34/arch/i386/Kconfig 2004-01-14 08:43:29.000000000 +0100 @@ -820,6 +820,14 @@ depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI)) default y +config REGPARM + bool "Use register arguments (EXPERIMENTAL)" + default n + help + Compile the kernel with -mregparm=3. This uses an different ABI + and passes the first three arguments of a function call in registers. + This will probably break binary only modules. + endmenu diff -u linux-34/arch/i386/Makefile-o linux-34/arch/i386/Makefile --- linux-34/arch/i386/Makefile-o 2003-09-28 10:53:14.000000000 +0200 +++ linux-34/arch/i386/Makefile 2004-01-13 20:16:32.000000000 +0100 @@ -47,6 +47,8 @@ cflags-$(CONFIG_MCYRIXIII) += $(call check_gcc,-march=c3,-march=i486) $(align)-functions=0 $(align)-jumps=0 $(align)-loops=0 cflags-$(CONFIG_MVIAC3_2) += $(call check_gcc,-march=c3-2,-march=i686) +cflags-$(CONFIG_REGPARM) += -mregparm=3 + CFLAGS += $(cflags-y) # Default subarch .c files diff -u linux-34/include/asm-i386/module.h-o linux-34/include/asm-i386/module.h --- linux-34/include/asm-i386/module.h-o 2003-05-27 03:00:24.000000000 +0200 +++ linux-34/include/asm-i386/module.h 2004-01-15 10:15:15.686788608 +0100 @@ -52,6 +52,12 @@ #error unknown processor family #endif -#define MODULE_ARCH_VERMAGIC MODULE_PROC_FAMILY +#ifdef CONFIG_REGPARM +#define MODULE_REGPARM "REGPARM " +#else +#define MODULE_REGPARM "" +#endif + +#define MODULE_ARCH_VERMAGIC MODULE_PROC_FAMILY MODULE_REGPARM #endif /* _ASM_I386_MODULE_H */
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