svn commit: r190105 - head/sys/sparc64/sparc64

[Marcel Moolenaar]

On Mar 20, 2009, at 6:36 AM, Marius Strobl wrote:

>>> Log:
>>> There's no need to wrap kdb_enter() in #ifdef KDB as it's always
>>> available.
>>
>> That's not quite how it works.
>>
>> option KDB is used to build the kernel with debugging features
>> that could impact performance, security and/or functionality.
>> In this case it's not so much a matter of whether kdb_enter()
>> is defined or not, but rather whether the kernel should respect
>> -d.
>>
>
> That's generally true but the places where I removed
> #ifdef KDB don't have an impact on security, performance
> doesn't matter and -d still does nothing if there's no
> debugger available (which in turn would require options
> KDB, at least according to documentation). I'm not sure
> what your're actually trying to say; following your
> logic strictly would mean that subr_kdb.c shouldn't be
> standard but only compiled in when options KDB is
> present.

The functions in subr_kdb.c have been made standard (i.e
non-optional) so that they can actually be used safely
from modules without having to worry about whether the
kernel has some option enabled. So, option KDB doesn't
control their visibility.

A debugger is present when either DDB or GDB is defined.
So, option KDB doesn't control that either.

Option KDB doesn't do much. For the most part it guards
code that results in entry into the debugger. For serial
consoles it changes the behaviour of the driver when a
serial break is detected. It also enabled the checking
for the alternate break sequence. Both you may not want
to do in production.

Granted there's no granularity. You want different
options for different cases so that you can enable or
disable code independently. That we never could do
before KDB, and we never did afterwards...

-- 
Marcel Moolenaar
xcllnt at mac.com