* Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> one system with 4g installed ( there is 1g hole)
>
> when 4G installed.
> BIOS put ACPI etc need the hole
> [ 0.000000] BIOS-provided physical RAM map:
> [ 0.000000] BIOS-e820: 0000000000000000 - 000000000009bc00 (usable)
> [ 0.000000] BIOS-e820: 000000000009bc00 - 00000000000a0000 (reserved)
> [ 0.000000] BIOS-e820: 00000000000e3000 - 0000000000100000 (reserved)
> [ 0.000000] BIOS-e820: 0000000000100000 - 00000000bffa0000 (usable)
> [ 0.000000] BIOS-e820: 00000000bffa0000 - 00000000bffae000 (ACPI data)
> [ 0.000000] BIOS-e820: 00000000bffae000 - 00000000bfff0000 (ACPI NVS)
> [ 0.000000] BIOS-e820: 00000000bfff0000 - 00000000c0000000 (reserved)
> [ 0.000000] BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
> [ 0.000000] BIOS-e820: 00000000ffb00000 - 0000000100000000 (reserved)
> [ 0.000000] BIOS-e820: 0000000100000000 - 0000000140000000 (usable)
> so in kernel resource will be reserved for 0xbffa0000 - 0xbfff0000 for ACPI
> 0x100000 - 0xbffa0000 for RAM...
btw., sidenote, it would be nice to enhance the e820 table printout
with size and hole info as well. I did this manually yesterday in
another mail:
BIOS-provided physical RAM map:
BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) 0.639 MB RAM
BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved) 0.001 MB
[ hole ] 0.250 MB
BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved) 0.125 MB
BIOS-e820: 0000000000100000 - 000000003ed94000 (usable) 1004.5 MB RAM
BIOS-e820: 000000003ed94000 - 000000003ee4e000 (ACPI NVS) 0.7 MB
BIOS-e820: 000000003ee4e000 - 000000003fea2000 (usable) 16.3 MB RAM
BIOS-e820: 000000003fea2000 - 000000003fee9000 (ACPI NVS) 0.3 MB
BIOS-e820: 000000003fee9000 - 000000003feed000 (usable) 0.15 MB RAM
BIOS-e820: 000000003feed000 - 000000003feff000 (ACPI data 0.07 MB
BIOS-e820: 000000003feff000 - 000000003ff00000 (usable) 0.004 MB RAM
[ hole ] 1.0 MB
[ hole ] 3072.0 MB
it would be extremely useful to have that in the printout, to see
the physical address space layout at a glance. Small holes are easy
to miss, and e820 entry sizes are hard to judge at a glance.
To make this fit well, i'd suggest to drop the 'BIOS-e820: ' prefix
- it's redundant.
Ingo
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