Re: CVS commit: src/sys

[David Young <dyoung%pobox.com@localhost>]

On Wed, Nov 18, 2009 at 03:51:02AM +0000, YAMAMOTO Takashi wrote:
> > Log Message:
> > Add a kernel configuration flag, SPLDEBUG, that activates a per-CPU log
> > of transitions to IPL_HIGH from lower IPLs.  SPLDEBUG is only available
> > on i386 and Xen kernels, today.
> > 
> > 'options SPLDEBUG' adds instrumentation to spllower() and splraise() as
> > well as routines to start/stop debugging and to record IPL transitions:
> > spldebug_start(), spldebug_stop(), spldebug_raise(), spldebug_lower().
> 
> this seems too ad-hoc to me.

If you have suggestions for providing a comparable function that is less
ad-hoc, let me know.

> - please don't put MD code like this in kern/.  IPL_ values can't be
>   compared with >= in MI code.  return_address.9 is in man.i386.

Thanks for pointing this out.  I am not going to move it from sys/kern/,
since it is fairly easy to make it MI.  I will compare IPL values with
== and !=, and write an MI stub for return_address(9) that returns NULL
on non-i386.

> - there are other places where the spl value is modified.
>   eg. interrupt stubs, lock stubs, etc.

Code references, please?

> - can you explain "cpu_index(ci) > MAXCPUS" and "cpu_index(ci) >= MAXCPUS" ?

Typo.

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933