Sketch wrote:
>
> On Fri, 3 Dec 1999, Robert G. Brown wrote:
>
> > Finally I noted that I could boot the system with the linux-up kernel
> > (uniprocessor) after a clean install. I discovered further that the
> > kernel was only identifying the system as having 64 MB of memory instead
> > of the 384 MB it actually has. No problem, I added the usual append
> > line to lilo.conf and voila! The system would boot EITHER UP or SMP. A
> > bit disappointing to learn a) that even a driver-free SMP 2.2 kernel +
> > aic7xxx driver won't boot in at least this system with only 64 MB to
> > boot in -- have no idea where the failure lives, but it is most annoying
> > and occurs consistently with 2.2.5 (RH 6.0) 2.2.10 (homemade), 2.2.12
> > (RH 6.1) and 2.2.13 (homemade); and b) that 2.2 kernels still don't
> > autodetect memory on at least some systems that aren't THAT old.
>
> I have two Supermicro DBE (BX) boards at work with dual 400's, both with
> 256MB of RAM. One is running RH5.2 upgraded to 2.2.13 with software raid1
> on IDE, the other is a clean RH6.1 install with a Mylex DAC960. Both have
> 3c59x NICs, and neither will recognize more than 64MB of RAM.
>
> My guess is it's either an issue with recent Supermicro (SMP?) boards, or
> Redhat's LILO is broken and forces 64MB unless told otherwise. I have not
> used Redhat with 2.2 on any non-supermicro boards with more than 64MB of
> RAM, so I can't rule out the second possibility.
>
> --
> Sketch
kernel has nothing to do with it. These boards (as well as P6DGE -- 440 GX
chipset) have a BIOS bug -- if power management in BIOS is disabled, only 64 MB
of RAM will be detected by 2.2.x kernels. If you enable power management in
BIOS, but disable all its features, the correct amount of RAM will be detected
and no adverse effects will be observed. I run these borads on production
servers. Kernel 2.3.x uses a different mechanism for memory detection and does
not have (or will not have) this problem. However, a few lines patch needs to
be applied in order to take care of another memory misdetection fenomenon (I
think it will misdetect 900 MB without the patch; the same situation occurs on
some Compaq boxes and the patch was submitted to Linus for inclusion -- please
view the previous messages of the week in this list). I have not tested these
boards deeply with 2.3.x kernels but I think I have observed a 900 MB
misdetection bug.
--
----------------------------------------
Constantine Gavrilov
Unix System Administrator and Programmer
Orbotech
Yavne 81102, Israel
Phone: (972-8)-942-3064
Fax: (972-8)-942-3800
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