Re: 2.2.0pre1 OOPS on boot.

Steven N. Hirsch (shirsch@adelphia.net)
Wed, 30 Dec 1998 09:43:16 -0500 (EST)


On 30 Dec 1998, Linus Torvalds wrote:

> Ahh, one last-minute thing in the 2.2.0-pre timeframe was to make a few
> more things depend statically on the CPU configuration.
>
> In particular, the thing that probably bit you is that as of 2.2.0-pre1,
> the CONFIG_M586 define implies that the target machine _has_ to support
> the TSC. This was simply because the SMP scheduling code came to depend
> on the TSC for certain things, and it's too timing critical to do other
> than as a compile-time define.
>
> As that meant that CONFIG_M586 had to imply a TSC when compiling for
> SMP, it made no sense to not enforce that assumption in other places
> too. That's notably "do_gettimeofday()".
>
> There is very arguably a bug there, but I'd say that it's just lack of
> documentation. I've now documented that CONFIG_M586 implies having a
> TSC, and made the bootup bug-check code actually verify that the runtime
> configuration matches what the kernel was compiled for and it should
> just panic clearly when it encounters unsupported hardware.
>
> So basically:
>
> - CONFIG_M386: Runs on anything
> - CONFIG_M486: requires "invlpg" and a working supervisor mode WP bit
> - CONFIG_M586: requires "rdtsc"
> - CONFIG_M686: requires a non-broken local APIC when running SMP

Linus,

2.0.0-pre1 blows up in the 'swapper' task at boot time. Machine uses a
gen-u-ine Pentium P166 which alleges support for TSC. Kernel is not built
for SMP. I'm rebuilding with CONFIG_M486 and will let you know if this
comes up.

Steve

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