Phil Wilshire wrote:
> What is apic ???
The APIC is a chip which remap IOs and IRQs of your computer to the
CPU(s).
This is needed on MPS ( Multi Processor System ) , cause you have
on all your system 1 IO mapping and 1 Irqs mapping and these one have
to be remapped to 1 CPU or shared between all CPU ( symetric system ).
> HOw does it work ???
On initialisation of your SMP system , you first boot on 1 CPU
(Boot Processor) and all the IOs and IRQs are remapped to this one.
Then your OS ( working up to now in single-CPU mode ) while booting ,
look for APIC structures (MP structure)in the Bios area
( Look at the Multi Processor specifications currently v1.4
on the Intel-developers website http://developer.intel.com ).
Then your OS switch to multi-CPU and programm the APIC to redirect all
the physical IRQs ( depending on OS ) to one (Asymetric) or all
(Symetric) CPU,
and idem for IOs remapping.
On both configuration , there is then :
1 BSP (BootStrapProcessor) and 1 or more AP(s)
(ApplicationProcessor(s)).
> What is Mtrr ??
MTRR is Memory Type Range Register
On Intel Pentium Pro/Pentium II systems the Memory Type Range
Registers (MTRRs) may be used to control processor access to memory
ranges. This is most useful when you have a video (VGA) card on a
PCI or AGP bus. Enabling write-combining allows bus write transfers
to be combined into a larger transfer before bursting over the
PCI/AGP bus. This can increase performance of image write operations
2.5 times or more.
( extrait from linux-kernel documentation )
> What is the TLB Cache ???
no more idea .. :(
Concerning the SMP functions , I recommend you to see
* the doc. of linux kernel : Documentation/smp.tex
* and MP spec of intel.
Explaining is always a good challenge for our knowledge.
Tell me if I'm wrong somewhere !
-- KUMSTA Christophe
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