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-   -   Why does acpi list CPU0 as CPU1 on a single CPU machine? (http://www.linuxquestions.org/questions/slackware-14/why-does-acpi-list-cpu0-as-cpu1-on-a-single-cpu-machine-575255/)

mdmaddux 08-07-2007 12:29 AM

acpi questions
 
I am running Slack 12.0 - generic smp kernel - with acpi on a laptop with one cpu, cpu0. (Pentium M)...

In /proc/acpi/processor I show CPU1 with a processor id of 0.
In /sys/devices/system/cpu/ shows cpu0.

Acpi docs show "ACPI might enumerate the CPUs differently - this is the ID the ACPI system uses to identify the CPU"

My question is, why does acpi not show the processor as CPU0 in /proc?

Might this have something to do with the acpi muddle? Say, a third-party program which expects /proc/acpi/processor/CPU0? Or is /sys the primary source for acpi status? Is /proc/acpi deprecated?

Finally, if all I want to do is recompile my distribution kernel (2.6.21.5-generic-smp) with one tiny little change (CONFIG_HOTPLUG_CPU) must I go through the 'make modules' 'make modules_install' steps or can I just copy bzImage over my existing kernel? And run lilo, per habit.

Thanks, this is my first posting here here...

mdmaddux 08-07-2007 06:01 PM

Done my homework, read the docs
 
OK. Got it. Both problems are trivial.

I think /proc is what's happening, and is deprecated while /sys is a lotta stuff, mostly pnp hardware states, registers and variables. No conflict. Both exist only in memory and are not disk files.

As for recompilation, I just took the .config from current working kernel, modified it (enabled HOTPLUG_CPU but added no modules, did 'make bzImage' (instead of make (default 'all')), renamed and copied to /boot, inserted System.map, ran lilo and rebooted.

And now I can echo mem >/sys/power/state and get the suspend to ram function.

Which goes to show that just formulating the question in a post is often the road to answering the question.

Thanks for the forum.


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