ia32e, er EM64T that is...

[Mogens Kjaer]

Alan Cox wrote:
> On Mon, Sep 06, 2004 at 10:11:51AM -0700, Jesse Keating wrote:
> 
>>I guess a better question: With kernel 2.6, is there any need to have a 
>>specific ia32e vs amd64 kernel?  Are all the differences worked out at 
>>runtime and thus a non-issue?  Thanks.
> 
> 
> em64t as Intel currently call it is pretty close to the x86-64 architecture
> so its not too bad a clone. It lacks prefetch/prefetchw which can also be 
> used by some fancy user space stuff like image processors. It also lacks
> a hardware IOMMU so you may have performance problems going above about 3.5Gb
> of RAM depending on your other hardware.
>

Sorry for following up on an old thread...

I have a Xeon/EM64T machine with 4G.

FC3-32bit installs without problems, 4G available.

FC3 x86-64 doesn't install, no disks are found.

If I boot FC3 x86-64 installation with mem=3072M,
there are no problems.

I have to add mem=3072M to grub after the installation
to get a running system.

The funny thing is, if I write mem=4096M, it still
boots, but only 3G memory is available.

I can see from /proc/iomem that there are devices
starting at the 3G address, so my guess is that
I've run into the problem described above.

Is there any way to get a x86-64 kernel to use all
4G?

Mogens

-- 
Mogens Kjaer, Carlsberg A/S, Computer Department
Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
Phone: +45 33 27 53 25, Fax: +45 33 27 47 08
Email: mk at crc.dk Homepage: http://www.crc.dk