Re: acpi based pci gap calculation - v3

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Alok's observations about the ACPI PCI0._CRS() package ResourceProducer
AddressRangeMemory definitions is the same approach as my optional
PCI-DRAM approach. Possibly where we differ is in how much weight is
given to the DSDT values since I found whilst analysing several hundred
DSDTs over the past year or so that the values returned could often be
'iffy' or over-vealous.

For example, there's a bug in the DSDT of many Sony Vaios whereby the
Intel 945 PCI Root Bridge's TOLUD (Top Of Low User Dynamic ram) register
is defined as a 6-bit wide field rather than the actual 5 bits, and is
then used in _CRS() by the AML to calculate and set the min, max, and
length of a range that represents installed RAM.

I've also seen instances of large areas being reserved 'just in case'
which might be all very well for servers with realistic hot-plug
opportunities but definitely cramps the style for notebooks and most
desktops.

I've decided to publish my code so at least others evaluate it and get
some experience of real-world situations. It provides command-line
over-rides for all options so it is easy to try different policies, and
via sysfs it can be changed on-the-fly. I'm not going to propose it as a
patch-set for submission yet, though.

It'll be next week before I get chance to publish - so much to do, too
much fun to be had!

TJ.

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