On Sat, 20 May 2000, Christopher Thompson wrote:
> I have now completed and tested my second TSC patch. It is available at:
> http://hypocrite.org/linux/tsc.patch.new.tar.gz
>
> This works with 2.3.99-pre8 at least, probably most others. This one disables
> use of the TSC by an option in the configuration (i.e. make config, make
> menuconfig, whatever) and therefore has NO performance impact on TSC-enabled
> kernels. The disadvantage is that this is another option to set in your
> configuration.
Hmm, a while ago I prepared a patch to disable TSC via a "notsc" kernel
command line option. I needed it to test SMP support for TSC-less
systems. While it makes the kernel larger by a few instructions, all of
them are located in the init section and are discarded after a bootup.
There is no runtime impact on the patch.
I believe this one might be useful for someone. It applies cleanly to
2.3.99-pre8.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +diff -u --recursive --new-file linux-2.3.99-pre6-2.macro/arch/i386/kernel/setup.c linux-2.3.99-pre6-2/arch/i386/kernel/setup.c --- linux-2.3.99-pre6-2.macro/arch/i386/kernel/setup.c Fri Apr 14 19:40:25 2000 +++ linux-2.3.99-pre6-2/arch/i386/kernel/setup.c Tue Apr 18 22:10:16 2000 @@ -1535,6 +1535,18 @@ return p - buffer; } +#ifndef CONFIG_X86_TSC +static int tsc_disable = 0; + +static int __init tsc_setup(char *str) +{ + tsc_disable = 1; + return 1; +} + +__setup("notsc", tsc_setup); +#endif + int cpus_initialized = 0; unsigned long cpu_initialized = 0; @@ -1558,6 +1570,13 @@ if (cpu_has_vme || cpu_has_tsc || cpu_has_de) clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE); +#ifndef CONFIG_X86_TSC + if (tsc_disable && cpu_has_tsc) { + printk("Disabling TSC...\n"); + boot_cpu_data.x86_capability &= ~X86_FEATURE_TSC; + set_in_cr4(X86_CR4_TSD); + } +#endif __asm__ __volatile__("lgdt %0": "=m" (gdt_descr)); __asm__ __volatile__("lidt %0": "=m" (idt_descr)); diff -u --recursive --new-file linux-2.3.99-pre6-2.macro/init/main.c linux-2.3.99-pre6-2/init/main.c --- linux-2.3.99-pre6-2.macro/init/main.c Fri Apr 14 19:40:33 2000 +++ linux-2.3.99-pre6-2/init/main.c Tue Apr 18 09:01:58 2000 @@ -481,12 +481,12 @@ lock_kernel(); printk(linux_banner); setup_arch(&command_line); + parse_options(command_line); trap_init(); init_IRQ(); sched_init(); time_init(); softirq_init(); - parse_options(command_line); /* * HACK ALERT! This is early. We're enabling the console before
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Tue May 23 2000 - 21:00:22 EST