On 09/07/2016 10:24 AM, William Cohen wrote:
On 09/06/2016 03:39 PM, Mahmoud Hanafi wrote:
On 09/06/2016 12:34 PM, David Smith wrote:
On 09/06/2016 02:08 PM, Mahmoud Hanafi wrote:
On 09/06/2016 11:55 AM, David Smith wrote:
On 09/06/2016 01:37 PM, Mahmoud Hanafi wrote:
In my stap script I have some embedded C function that needs to make
some calls to external libraries. Is there I can link my script with the
external libs? Or do i need to add all the code I need into my script.
Basically you can't. A systemtap script gets compiled into a kernel
module (assuming you are using the default 'linux' runtime). A kernel
module can't access *any* user library.
Perhaps you should back up a bit and let us know what your external
library is trying to do.
The library is part of lustre. I need the functions that does address
translation to string values.
Can you point me to the library/function on lustre.org that you are
interested in?
You can't really copy userspace C code into systemtap. Systemtap tries
very hard to handle memory accesses safely (since otherwise you can
crash the kernel). We might be able to "translate" the userspace C code
into embedded C.
the function is defined here
http://osxr.org:8080/linux/source/drivers/staging/lustre/lustre/libcfs/nidstrings.c#0382
"libcfs_nid2str"
It would be nice to compile in something like this, because if there are changes later in the function it wouldn't require stap script changes.
Hi,
Isn't libcfs_nid2str a kernel function? For some kernel functions one
could use systemtap guru mode to directly call c functions in the kernel.
However, it doesn't look like this particular function is visible to code
outside the lustre module.
You might be able to include <linux/libcfs/libcfs.h> and clone the libcfs_nid2str
function using guru mode (-g) as a work around. At least that would
allow access
to the various defines and macros. Use the
systemtap/tapset/linux/tcp.stp as an
example of how to do the include and systemtap functions
(https://www.sourceware.org/git/?p=systemtap.git;a=blob;f=tapset/linux/tcp.stp;h=22fe2f08fda55c989d33cdcd776fa00736f4b7dd;hb=HEAD).
Not an ideal solution, but it might get you closer to what you want.
I've looked at the kernel's libcfs_nid2str() function a bit. Cloning the
function really isn't going to work. The function uses an internal
lookup table that you won't have access to.
If the nid can't be found in the lookup table, libcfs_nid2str() returns
a default string. Here's a simplified version of libcfs_nid2str() that
shows how it creates the default string:
__u32 addr = LNET_NIDADDR(nid);
__u32 net = LNET_NIDNET(nid);
__u32 nnum = LNET_NETNUM(net);
__u32 lnd = LNET_NETTYP(net);
...
snprintf(buf, buf_size, "%x@<%u:%u>", addr, lnd, nnum);
If that's acceptable, it should be fairly easy to do in systemtap.