Re: Comments about SMP

[Almudena Garcia]

though: is APIC still at that address?

I don't know, but we can search the current address reading from ACPI tables, so It's not problem.

Another question: I found a project called OSKit, what feels to be Mach 2.x branch.

What is the difference about gnumach and oskit?

In their repository, I found many files about SMP support

http://cvs.savannah.nongnu.org/viewvc/oskit/oskit/smp/x86/

May this files could be useful to our SMP support.

El dom., 3 feb. 2019 a las 20:14, Samuel Thibault (<samuel.thibault@gnu.org>) escribió:

Hello,

Almudena Garcia, le dim. 03 févr. 2019 19:45:21 +0100, a ecrit:
> At first time, I found that Mach 4 also had a implementation of cpu_number()
> (in kernel/imps/cpu_number.h), with this:
>
> static inline int
> cpu_number()
> {
>     return apic_local_unit.unit_id.r >> 24;
> }
>
> Later, also in Mach 4, I found an old implementation of APIC support. This code
> also existed in gnumach, but was removed in 2009/
>
> [2]http://git.savannah.gnu.org/cgit/hurd/gnumach.git/commit/i386/imps/apic.h?id
> =0266d331d780ff0e595eda337a3501ffbfea9330
>
> I see that this contains interesting structures to read ACPI registers. Why
> this code was removed? May could be interesting recover It fot SMP support.

Possibly. I don't know if it's still relevant with nowadays' hardware,
though: is APIC still at that address?

> But, in cpu_start() function, there are a call to intel_startCPU(). I was
> searching this function in Mach 4 and gnumach code. but I didn't find It.
>
> What must to do this function?

I guess it's the low-level function which tells the hardware that it
should actually make a given CPU start.  I don't know which function it
should be starting, though.

Samuel