Fwd: user space probe in ubuntu 14.04

Frank Ch. Eigler fche at redhat.com
Tue Sep 15 20:06:34 UTC 2015

Hi, Colin -

> This is a mistaken analysis.  /usr/sbin/mysqld is in
> mysql-server-core-5.5, not mysql-server-5.5, and therefore its debugging
> symbols are in mysql-server-core-5.5-dbgsym:

Thank you for the correction.  I must have misread the output from "dpkg -S". 

>   $ dpkg -c mysql-server-core-5.5-dbgsym_5.5.44-0ubuntu0.14.04.1_amd64.ddeb | grep 5b99
>   -rwxrwxr-x root/root  48818397 2015-07-16 23:50 ./usr/lib/debug/.build-id/7c/5b991d6ba0d7722a41f9a39e2915f6a354a1c7.debug

Indeed, and now dwarf-based function/statement probes can be resolved against

> The information that Gareth provided indicated that they already had
> mysql-server-core-5.5-dbgsym installed, so perhaps this problem is
> entirely explained by the NT_STAPSDT bit above.

The NT_STAPSDT part is actually completely separate.  It relates to
instrumentation compiled into the binary from <sys/sdt.h> macros, not
data from the -dbgsym files.  Activating that requires mysql configury
or buildroot tweaks to ensure the systemtap-provided
/usr/include/sys/sdt.h file is available.  In the Fedora .spec [1], this
is apprx. done by:

BuildRequires: [...] systemtap-sdt-devel [...]
cmake . [...] -DENABLE_DTRACE=ON  [...]

[1] http://pkgs.fedoraproject.org/cgit/mariadb.git/plain/mariadb.spec

- FChE

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