Re: [patch] SMP alternatives

[Eric W. Biederman]

Andi Kleen <ak@xxxxxxx> writes:

> Thanks. But without a per board DIMM mapping it's pretty useless, isn't it?

Nope.

Getting a per board chip select to DIMM mapping is fairly easy, you
just need a lookup table of:
(memory_controller, chip_select, channel, dimm_label)

Which if the motherboard vendor does not give it to you is pretty
straight forward to discover just by plugging a minimal memory configuration
into various slots.  We can already query in software what the
motherboard is so keeping a table like this in user space is
not a problem.

> One could detect the IO hole by reading the IORR MSRs or alternatively
> parsing the e820 map in /var/log/boot.msg

The problem is not detection but compensating for how it changes
the address.

I do agree that it would be nice if there was a standard for
BIOS's reporting this information.  In LinuxBIOS it is one of
those TODO list items we never quite get to.  But so far a user
space table has proved quite useful in practice.

Eric
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