[TUHS] PDP-8 (was: 2.11BSD cross compiler)

[grog@lemis.com (Greg 'groggy' Lehey)]

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On Thursday, 30 September 2010 at  6:50:29 -0700, Larry McVoy wrote:
>>>>  If you don't get the question you are not an OS person,
>>>> if you are, of course you get it.
>>
>> Hmm.  Am I expected to understand this?  Seriously, I don't know how
>> many people really wrote anything like swtch ().
>
> You'd be amazed at how many people did their own user level threads.
> Gotta write swtch() for that.

I think you're missing the joke.  But swtch () is a specific kernel
function in UNIX, though in this thread (excuse the pun) people seem
to be using it as a synonym for a scheduler.  And not many people need
to write their threading library by hand any more.

> And it's not swtch() so much as do you understand the stack frames?

That's a different issue.  Any programmer worth his salt needs to
understand the underlying hardware, including stack frames.  For my
personal understanding of them, see
http://www.lemis.com/grog/Documentation/PUS/porting_unix_software/obj.pdf
towards the end, or http://www.lemis.com/grog/Papers/Debug-tutorial/
for the kernel context, page 17 on.

> If you could look at the stack frames and give me a stack trace
> that's more or less the same thing.

(gdb) bt

The real question is not to get a stack trace, but to analyse it.

Greg
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