More trapframe panics

[Joe Holden]

On 26/01/2014 18:54, Warner Losh wrote:
>
> On Jan 26, 2014, at 9:04 AM, Juli Mallett wrote:
>
>> On Sun, Jan 26, 2014 at 7:07 AM, Jan Bramkamp <crest at rlwinm.de> wrote:
>>>
>>> Would increasing KSTACK_PAGES from two to three or four help? What are
>>> the trade-offs involved in choosing KSTACK_PAGES for something like the
>>> EdgeMax Lite?
>>
>>
>> That's exactly what needs to happen in all 64-bit MIPS kernels.  Unlike
>> some other architectures,  KSTACK_PAGES cannot simply be increased,
>> however.  All of the code which handles loading the kernel stack and
>> keeping it mapped, etc., assumes that it takes up exactly one TLB entry,
>> i.e. 2 pages.  One could simply double KSTACK_PAGES for 64-bit builds and
>> modify the code to support the case of 2 or 4 pages, which would keep the
>> code as gross as it is today and not buy much flexibility, but might be
>> worthwhile as a short-term fix.  Being able to support arbitrary values of
>> KSTACK_PAGES (or at least arbitrary multiples of 2 up to the maximum number
>> of wired TLB entries times 2) would be better.
>
> I hacked together a kludge that quadrupled this by going to the next larger page size for stack pages in the TLB, but hit something ugly when I did that... But I've lost that code, so maybe I should try again to see if I'm more clever the second time.
>
> This is one of the things that makes it hard to have a nice native build server on mips64...
>
> Warner
>
I have plenty of hardware (pretty much just spare ERLs) that you can use 
if you want - unless you can give

  me some ideas on other mips64 hardware that would be useful in which 
case I can make that available too.