Re: Request: increase in PCI bus limit

[Manfred Spraul]

> 
>    I'm working at a customer site with custom hardware. The 2.4.0 series 
> kernel almost works out of the box, but the machine has 52 PCI busses. 
> Plans are to produce a 4-way box which would have over 80 PCI busses. The 
> file include/asm-i386/mpspec.h allocates space for 32 busses in the 
> definition of the macro MAX_MP_BUSSES. 
>

How long is the MP structure?
smp_scan_config() reserves only 4 kB:

	reserve_bootmem(mpf->mpf_physptr, PAGE_SIZE);

reserving the actual size (mpf->mpf_physptr->mpc_length) could be
tricky.

It should be possible to dynamically allocate the memory for the busses:
It's not yet possible (smp_read_mpc() is called at a very early stage,
before kmalloc is initialized), but we must move it to a later stage
anyway:
some Compaq bios version need ioremap() in smp_read_mpc(), and we should
parse the ACPI tables for APIC descriptors (MADT, ia64 does that
already).

I'll add it to my TODO list.

--
	Manfred