Thanks for the info. The reserve param I refer to is the "reserve" param
from kernel-parameters.txt
"reserve= [KNL,BUGS] Force the kernel to ignore some iomem area"
On my number 2. I have been testing just giving 4 Gigs to the OS which ends
up getting cut into by the iomem addressing and then just trying to use the
remaining 12Gigs. However I have been running into trouble when I address
into the 7-8 Gig area. Could that be one of the hidden maps you mentioned?
Thanks
Tom
1) in arch/x86_64/kernel/e820.c the e820_reserve_resources function
the line if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
makes it so any region that
starts below the 4Gig mark but ends above 4Gig mark is ignored.
That is already gone in 2.6.13rc1.
2) I am unable to get all of my PCI devices to move there addressing
from the default values to the hole I have given it. I am getting
several errors of the form: "PCI: Cannot allocate resource region 8 of
bridge 0000:00:07.0". Some of my devices are moving to the proper
location.
Neither the code in drivers/pci/probe.c pci_read_bases which gets the
default addresses for the resources or /arch/i386/pci/i386.c
pcibios_allocate_bus_resources check to see if the address that are
being used are reserved. They just attempt to allocate the memory and
fail. It seams like a check should be made in one of these functions
and if the resources are reserved then the addresses should be
changed. (Note: 64 bit uses the i386 pci code that is why I am
pointing out potential errors in the i386 code)
Yes, that code is quite bad and in need of an overhaul. There
are other problems in there too. Also the default hole selection
algorithm is not very reliable and some BIOS tend to put
hidden mappings in there. Most likely it needs more support from ACPI.
I also noticed the reserve kernel param can only take ints so large
addresses can not be reserved
What reserve kernel param? mem= certainly supports more than 4GB.
-Andi
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