>Date: Thu, 5 Jul 2001 20:17:39 -0400 (EDT)
>From: maximum entropy <entropy@tappedin.com>
>
>I have an old Pentium running 1.5.  I'm trying to update it, but for some
>reason nothing after 1.5 will run on it.
>
>The following log shows it failing to boot -current from yesterday
>(/netbsd) then correctly booting 1.5 (/onetbsd).  Both are plain
>GENERIC kernels.
>
>Any ideas on what's wrong would be appreciated.
>
>>> NetBSD/i386 BIOS Boot, Revision 2.10
>>> (entropy@zippy.local, Thu Jul  5 05:13:48 EDT 2001)
>>> Memory: 635/48128 k
>Press return to boot now, any other key for boot menu
>booting fd0a:netbsd - starting in 0
>type "?" or "help" for help.
>> boot hd0a:netbsd -s
>booting hd0a:netbsd (howto 0x2)
>4532951+83004+324460 [65+263168+216671]=0x52c6f0
>WARNING: CAN'T ALLOCATE MEMORY SEGMENT (0x100000/0xf00000/0x1) FROM IOMEM EXTENT MAP!
>WARNING: CAN'T ALLOCATE MEMORY SEGMENT (0x1000000/0x2000000/0x1) FROM IOMEM EXTENT MAP!
>(At this point the system resets immediately).

I just found a workaround...I added the following options to the
kernel config, based on the output from the bootblocks.

options         REALBASEMEM=635
options         REALEXTMEM=48128

Now the machine boots 1.5W.  But these options were never needed
before on this machine (which has been running NetBSD since
1.2something.)  I strongly suspect that a bug has been introduced into
the memory probe routines after 1.5.

--
entropy -- it's not just a good idea, it's the second law.