Curious failure...

[Mike Isely]

On Fri, 3 Dec 1999, Robert G. Brown wrote:

> This is just to report an interesting problem I encountered trying to
> install RH 6.0 or 6.1 on a SuperMicro dual 300MHz PII with the older
> 440LX chipset.  Basically the install would go perfectly but when I
> tried to boot the new system, the boot would absolutely hang at the
> point where the aic7xxx driver was initializing.  This was quite
> maddening; given access to the system via a suitable boot floppy I tried
> all sorts of things including the installation of a monolithic kernel
> and so forth.
> 
> 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.
> 

If the aic7xxx driver maps the adapter into memory space (I think it
does), then it could have mapped over what it thought was empty space, but
because there was real memory there (that went undetected), Bad Things
might have resulted...  The same scenario would be possible for any memory
mapped device (thinking about the video card here). 

  -Mike


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