Messages in this thread | | | Date | Wed, 1 Feb 2006 11:28:10 +0100 | From | Mikael Pettersson <> | Subject | Re: patch to make 2.4.32 work on i486 again |
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Jacek Lipkowski writes: > Booting the 2.4.32 kernel compiled for a i486 on an i486 box fails, > because "Kernel compiled for Pentium+, requires TSC feature!" (printed > from check_config() include/asm-i386/bugs.h). To reproduce, select 486 in > the kernel configuration and grep CONFIG_X86_TSC .config > > Seems strange that no one noticed this, am i the only one still using 486 > boxes? :) > > Jacek > > Simple patch against vanilla 2.4.32: > > --- arch/i386/config.in.old 2006-01-30 22:57:21.000000000 +0100 > +++ arch/i386/config.in 2006-01-30 23:00:55.000000000 +0100 > @@ -65,6 +65,7 @@ > define_bool CONFIG_X86_POPAD_OK y > define_bool CONFIG_RWSEM_GENERIC_SPINLOCK n > define_bool CONFIG_RWSEM_XCHGADD_ALGORITHM y > + define_bool CONFIG_X86_TSC n > fi > if [ "$CONFIG_M486" = "y" ]; then > define_int CONFIG_X86_L1_CACHE_SHIFT 4 > @@ -72,6 +73,7 @@ > define_bool CONFIG_X86_ALIGNMENT_16 y > define_bool CONFIG_X86_PPRO_FENCE y > define_bool CONFIG_X86_F00F_WORKS_OK n > + define_bool CONFIG_X86_TSC n > fi > if [ "$CONFIG_M586" = "y" ]; then > define_int CONFIG_X86_L1_CACHE_SHIFT 5
This is a known limitation of the 2.4 kernel's configuration system: a single round of make ${foo}config doesn't always reach a fixpoint with regard to the derived options. CONFIG_X86_TSC is the standard example of this: switching from a stable .config with TSC (say i686) to one without (say i486) leaves a stray definition of CONFIG_X86_TSC behind in .config. Solution: run 'make oldconfig' after flipping the user-selectatable options.
Your patch may fix the TSC case, but there are probably more cases like this in 2.4.
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