Re: system time issue

["Richard B. Johnson" <root _at_ chaos.analogic.com>]

On 9 Jan 2002, Sipos Ferenc wrote:

> Hi!
> 
> I have a redhat 7.2 box, and compiled the latest 2.4.18pre2 kernel with
> the 2.4.18pre2aa1 patches in order to use gcc pre 3.1. When I shutdown
> my system with the new kernel, it writes out normally: syncing system
> time with hardware time, and with gcc 2.96 compiled kernels, everything
> is ok, but with this kernel, after reboot the bios beeps and the
> hardware time and date stands at the beginning, so I have to setup
> manually to continue the post process. I think, gcc pre3.1 miscompiles
> something in the kernel.
> 

Here is a test program I would like everybody to try. It is a module
but is not intended to actually be implimented in the kernel as a
module once eveybody finds out that it will reliably cold-start even
a SMP machine. This is for Intel CPUs only.

The purpose of the module is to execute two simple CPU instructions
in kernel mode. This forces a processor reset, just like hitting
the reset button.

There are two scripts that you should look at because you might
want to go to single-user mode first and unmount your disk(s)
if your `kill -1` command kills you as well as everybody else.

I think all the complex reboot stuff in the kernel can be removed
and the simple two-line assembly substituted.

If anybody finds that executing the 'open()' of this test module
does not cause a processor reset in which a cold boot is forced,
please let me know.

Once most everybody has faith that this will produce a clean
reboot, somebody, maybe Allan can use it to replace the reboot
code in the kernel.

The code works by disabling paging while executing code where
there is not a 1:1 physical/virtual page mapping. I have never
found a system, even one with two CPUs that did not instantly
reset.

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (797.90 BogoMips).

    I was going to compile a list of innovations that could be
    attributed to Microsoft. Once I realized that Ctrl-Alt-Del
    was handled in the BIOS, I found that there aren't any.

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