Re: Comments about SMP

[Samuel Thibault]

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