is dtrace usable?
Robert Watson
rwatson at FreeBSD.org
Sat Mar 6 16:00:12 UTC 2010
On Sat, 6 Mar 2010, Alexander Leidinger wrote:
>> Take a look at the DTrace configuration information here:
>>
>> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/dtrace.html
>
> I've just reread it (despite the fact that I already used it). Some
> comments:
>
> Last time I tried, I didn't see any problems by adding
> makeoptions WITH_CTF=yes
> to the kernel config instead of doing
> make WITH_CTF=1 kernel
>
> Did I miss something, and if not, shouldn't we tell about the
> makeoptions part instead (a kernel rebuild later will not cause
> trouble when someone forgets to do the WITH_CTF part as it is already
> in the kernel makefile)?
I'll leave John to answer this one, CC line broadended.
> What is DDB_CTF doing? Some additional dtrace access in ddb? I didn't had it
> before but the dtrace probes I had in KLDs worked without problems when
> running dtrace probes from userland.
This is a poorly named kernel option, and should probably be changed. This
has to do with the kernel loading CTF information for kernel modules. My
recollection is hazy, but it may well be required in order for fbt to be used
with modules.
Robert N M Watson
Computer Laboratory
University of Cambridge
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