Is there a way to tell stap where to find include headers?

Is there a way to tell stap where to find include headers?

[Lan, Jay]

Hi,

I am new to systemtap and am writing a systemtap script on Mellanox OFED ('mofed') kernel modules. The mofed provides its subset of kernel include files at different location from that of a kernel-devel. The mofed header files should be checked ahead of those from kernel-devel.

Is there a way to tell stap where to find the mofed header files? I searched the web and read man pages, but came out nothing... Any pointer is appreciated! TIA!

Regards,
Jay

Re: Is there a way to tell stap where to find include headers?

[Frank Ch. Eigler]

"Lan, Jay" <jay.lan@hpe.com> writes:

> I am new to systemtap and am writing a systemtap script on Mellanox
> OFED ('mofed') kernel modules. The mofed provides its subset of kernel
> include files at different location from that of a kernel-devel. The
> mofed header files should be checked ahead of those from kernel-devel.
>
> Is there a way to tell stap where to find the mofed header files?

systemtap looks for headers in a couple of contexts: tracepoints (for
trace("...") probes), type declarations (for @cast ops).  For the
former, not sure.
For the latter,
   @cast(ptr, "typename", "kernel</path/to/header>")->field
does work.

- FChE

Re: Is there a way to tell stap where to find include headers?

[Lan, Jay]

Thanks for quick reply, Frank!

In the exmaple you mentioned
    @cast(ptr, "typename", "kernel</path/to/header>")->field
I assume 'kernel' tells stap to look at /lib/modules/<uname -r>/build/include/. But for external kernel modules such as mofed, how can I tell stap what other location to look at? The mofed headers are installed to /usr/src/ofa_kernel/.../include/.

Thanks,
Jay

On 03/07/2019 06:32 PM, Frank Ch. Eigler wrote:

"Lan, Jay" <jay.lan@hpe.com><mailto:jay.lan@hpe.com> writes:



I am new to systemtap and am writing a systemtap script on Mellanox
OFED ('mofed') kernel modules. The mofed provides its subset of kernel
include files at different location from that of a kernel-devel. The
mofed header files should be checked ahead of those from kernel-devel.

Is there a way to tell stap where to find the mofed header files?



systemtap looks for headers in a couple of contexts: tracepoints (for
trace("...") probes), type declarations (for @cast ops).  For the
former, not sure.
For the latter,
   @cast(ptr, "typename", "kernel</path/to/header>")->field
does work.

- FChE

Re: Is there a way to tell stap where to find include headers?

[Frank Ch. Eigler]

Hi -

On Fri, Mar 08, 2019 at 02:55:11AM +0000, Lan, Jay wrote:
> In the exmaple you mentioned
>     @cast(ptr, "typename", "kernel</path/to/header>")->field

> I assume 'kernel' tells stap to look at /lib/modules/<uname-r>/build/include/.

That's a good guess, but not quite.  It tells stap to invoke the
kernel build compiler / cflags to process the given header.  There
is an implicit "-Ipath" there, but that doesn't apply to /full/path names.

> But for external kernel modules such as mofed, how can I tell stap
> what other location to look at? The mofed headers are installed to
> /usr/src/ofa_kernel/.../include/.

Have you tried @cast(ptr,"foobar","kernel</usr/src/ofa..../include/foo.h")  ?

- FChE