Re: Stap option to specify location of kernel binary

[Roland McGrath <roland at redhat dot com>]

> Actually stap -r doesn't seem to work. 

Ok.  I'll admit that I was really only speaking for eu-* -K options, which
is the same as what stap -r feeds for the debuginfo-finding side of things.
The rest of the nits are in systemtap itself.

> Module directory /lib/modules//home/srikar/work/linux-2.6.24.1/build
> check failed: No such file or directory

That is obviously dumb.  The running-make bit needs to check for an
absolute directory name.

> I tried passing a release (2.6.24.1)as argument to -r option.
> Infact the same release as the current kernel.

Giving 2.6.93.9 is just the same as giving /lib/modules/2.6.93.9 instead.
It certainly doesn't make any sense to expect that just telling it any
simple string magically makes it know where to find your kernel binary.

> Another trivial issue is the stap seems to override pass level to 4 when
> user tries to explicitly use -p5 along with -r option. I verified this
> by seeing the code.  The user would have to use staprun to actually use
> the module created with -r option. 

It sounds like the one stap option does too much as well as too little!
It's probably fine for the simpler command line to indicate build without
run, i.e. just -r alone can mean both "build only" and "specified directory
for kernel & .ko binaries".  But they should be available as independent
flags somehow, and not just with the ever-obscure -p5.


Thanks,
Roland