Re: 4GB of memory and NForce4SLI

Giuseppe Ghib=F2 wrote:
> Thomas Backlund wrote:
>=20
>> Giuseppe Ghib=F2 wrote:
>>
>>> I tried currently 2006.0 with kernel 2.6.12.18mdksmp-x86_64 into
>>> a MSI K8N Diamond Plus motherboard with Athlon64-X2 4800. The
>>> motherboard has chipset Nforce4-sli and 4 modules of 1GB each.
>>>
>>> Currently the BIOS sees 3328MB of memory and in such way
>>> it correctly boots with 2.6.12.18mdksmp and free shows
>>> 3350260 kB free mem with the 'free' command.
>>> How to obtain the rest of 700MB of memory? OK, there is the addressin=
g
>>> space for PCI, etc., but for instance other mobos shows more than 3.3=
GB.
>>> E.g. on Tyan 2885 I see 4096MB in BIOS and 3559132 with 'free'.
>>>
>>
>> Atleast MSI nforce4 boards does only support ~3.5GB memory without the=
=20
>> "memory hole" enabled...
>>
>>> The K8N Diamond has an option in BIOS to "Enable Hardware Memory Hole=
",
>>> which enable memory remapping around the memory hole. The CPU needed
>>> for this option is at least stepping E0. A64-4800X2 is stepping E6
>>> so should be supported. Once the "Hardware Memory Hole" has been
>>> enabled the BIOS sees 4096MB of memory. But the kernel is no
>>> longer able to boot. Latest logs were:
>>>
>>> ...
>>> Freeing unused kernel memory: 196k freed
>>> Kernel panic - not syncing: No init found. Try passing init=3D option=
=20
>>> to kernel
>>>
>>
>> you need to tell it how much memory you have using the "mem=3D" boot=20
>> option...
>=20
>=20
> I tried with mem=3D... too but up to 4096m you always get only 3.25GB.
> With mem=3D4099m xfs is not starting anymore, and with bigger values su=
ch
> as mem=3D4103m, or even mem=3D5120m, mem=3D5G it
> goes in kernel panic.
>=20
>>
>> check this:
>> http://hardware.mcse.ms/archive20-2005-8-216970.html
>>
>> at the end one user states:
>>
>> <quote>
>>
>>> Found the solution. Set the BIOS to Fill Memory Hole and then told Li=
nux
>>> it had 5G, i.e. mem=3D5G on the boot line.
>>>
>>> BTW a mem=3D line is required if when you set the BIOS to Fill Memory=
=20
>>> Hole,
>>> without it you'll get a kernel panic when you boot. The FC3 installer=
=20
>>> just
>>> does a straight boot so it will panic on a machine with the Fill Memo=
ry
>>> Hole option set in the BIOS.
>>
>>
>> </quote>
>>
>>
>>> I tried also with kernel-2.6.14.2mdksmp-x86_64 but same results. Even
>>> with kernel-linus-2.6.16.15mdksmp-x86_64 gives the same (plus error
>>> during 3ware modules scsi probing:
>>>
>>> scsi: host 0 channel 0 id 0 lun 0x5a5a5a5a5a5a5a5ahas LUN larger than
>>> currently supported.
>>>
>>> Bugs in kernel IOMMU?
>>>
>>
>> you can also try booting with iommu=3Dforce
>=20
>=20
> didn't help.
>=20
>>
>>
>>> Bye
>>> Giuseppe.
>>>
>>
>=20

According to this paper:

http://techfiles.de/dmelanchthon/files/memory_hole.pdf

it seems the memory hole can be shrinked by limiting
the AGP Aperture size. Unfortunately in the K8N Diamond I don't see
and BIOS option (furthermore it has PCI-express and not AGP slot)
to do this.

Bye
Giuseppe.