On Sun, Feb 22, 1998 at 07:40:38PM -0600, Chuck Cranor wrote:
> Ted is reporting two different problems: 
>  [1] with PMAP_NEW he is getting random reboots and strange 
> 	"file not found" problems
>  [2] with !PMAP_NEW he is getting a ptdi panic
> 
> i have been attempting to reproduce [1], without success.
> 
> [2] is the one you've seen.   since uvm has different kernel memory
> usage than bsd vm, it is possible that the guess that the kernel makes
> for number of kernle PT pages could be off, thus the ptdi panic.
> so i'm not that worried by it at this point (especially since 
> the new pmap dynamically allocates kernel PT pages via the freebsd
> pmap_growkernel interface).

Well, at 64M of physmem, the nkpde guess/computation results in enough
PDEs for all the kvm possible (i.e. 0xffffffff - 0xf0000000 - 4 = 252M).
So if you use all that up anyway, something bad is happening. Also, I've
never run out of kvm before on this machine. I am not using any extra kvm
(like because of a larger number of bufpages). So, I am worried. 

When I saw Ted's messages, it seemed to me that the 2 different panics
were just caused by different reactions of the new pmap module and the
old one to running out of kvm (i.e. they end up panicking in different
ways), but are symptoms of the same problem.

Anyway.. it's being worked on, hopefully it's fixed soon.

- Frank