Re: cpu-2.5.64-1

Zwane Mwaikambo
2003-03-11T08:17:48Z

On Tue, 11 Mar 2003, Zwane Mwaikambo wrote:

> Have you had an opportunity to test this code yet? If you can't get that
> large a 32bit SMP box, you could fire off some 'extra' cpus on i386 then
> fail them during boot around cpu_up, making sure to put the failed cpus
> somewhere in the middle of your cpu map so that not only do you get a
> sparse map but some on the other side of 32.

Something crackpot ala;

The new boot process would look something like this (pseudo code as i
don't know the types you use yet), just watch out for num_booting_cpus
users.

/* the fake cpus we're going to fire up and fail */
cpumask_t fake_cpu_map = (1 << 13) | (1 << 14) | (1 << 15);

arch/i386/kernel/smpboot.c

smp_boot_cpus() {
...
Dprintk("CPU present map: %lx\n", phys_cpu_present_map);
for (bit = 0; bit < NR_CPUS; bit++) {
if ((1 << bit) & fake_cpu_map))
set_bit(bit, cpu_callin_map);
....
}
}

do_boot_cpu() {
cpu = ++cpucount;
if ((1 << cpu) & fake_cpu_map) {
/* you could probably stop here and set the boot error
* without decrementing the cpucount */
goto skip_hardware_wakeup_bits;
}

skip_hardware_wakeup_bits:
return boot_error;
}

Anyway coffee is wearing off and i must sleep...

Zwane
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