On Thu, 23 Aug 2007 14:38:45 +0530
Vivek Goyal [off-list ref] wrote:

Does your kernel 2 boot normally? I mean through BIOS and boot-loader?
This explanation seems to be suggesting that because PM and ACPI is
disabled, kernel 2 does not search for HPET. If this is the case,
this kernel will not boot even through normal boot-loader and will
try to use PIT instead?

If so, it is not an kexec issue at all.

Thanks
Vivek

kernel 2 boots normally through BIOS and boot-loader. I agree with your
explanation.
It seems that kernel 2 can't enable PIT, when it is executed by kexec.
As kernel 1 disabled HPET(IRQ0 source) and PIT is "broken"(or isn't
enabled) IRQ0 are not triggered at all, and kernel 2 hangs.
As kernel 2 boots normally through BIOS and boot-loader, than
additional code needed(in Linux kernel init code) for PIT or ACPI
or APIC initialization, I mean the same code as executed on BIOS stage.
I agree that it's not an kexec issue. But can we use my fix as a
workaround(to make kexec work) until PIT will be fixed?
Everything above is correct for i386/x86_64 RT(2.6.23-rc2-rt2) kernel
and for i368 "plain"(2.6.23-rc3) kernel. Bug isn't reproduced in 2.6.23-rc3
x86_64 kernel, because x86_64 code never disables HPET. So on every
boot(initiated by kexec or BIOS) IRQ0 are triggered.