2.4.26 doesn't boot on a 386 without "Unsynced TSC support"

[Erik Mouw]

Hi,

I tried to boot 2.4.26 on my good old 386 board, but got a kernel
panic:

  CPU: 386
  Kernel panic: Kernel compiled for Pentium+, requires TSC feature!

The error message comes from the function check_config() in
include/asm-i386/bugs.h (thanks to wli for figuring out faster than I
did).

I am sure I selected support for a 80386 CPU, so the error message
looks wrong to me. CONFIG_M586TSC is not set, but CONFIG_X86_TSC is
enabled by default. The only way to disable it, is to enable "Unsynced
TSC support", (CONFIG_X86_TSC_DISABLE).

The help for CONFIG_X86_TSC_DISABLE mentions to use it for "NUMA
mult-mode boxes, laptops and other systems suffering from unsynced TSCs
or TSC drift, which can cause gettimeofday to return non-monotonic
values." A simple 80386 board doesn't belong to these, and I can't
remember having problmes with gettimeofday() in the past (IIRC the
board last ran linux-1.2 or 2.0).

My question is: is this a code bug, or a documentation bug? Right now,
I guess 2.4.26 will not run on anything < Pentium without
CONFIG_X86_TSC_DISABLE enabled.


Erik

-- 
+-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 --
| Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands
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