SystemTapのソースを表示

[[Category:Kernel]]
[[en:SystemTap]]
[[zh-cn:SystemTap]]
[http://sourceware.org/systemtap/ SystemTap] は動作中の Linux システムからの情報収集を簡略化するためのフリーソフトウェア(GPL)インフラストラクチャを提供します。

==SystemTap==

[[AUR]] から SystemTap をインストールします: {{AUR|systemtap}}。

上流での最新のリリースと比較します [https://sourceware.org/systemtap/wiki/SystemTapReleases]。

[https://sourceware.org/git/?p=systemtap.git;a=summary] にあるソースからビルドすることも考慮してください。新しいカーネルやディストロのサポートは最初にここに現れます。

==標準的なカーネル==

すくなくとも {{Pkg|linux-headers}} がインストールされている必要があります。

Because Arch permanently strips debugging data from its distributed binaries (including the kernel),
many normal/fancier systemtap capabilities are simply not available, so many examples at ''/usr/share/doc/systemtap/examples'' will not work.  However, see the [https://sourceware.org/systemtap/man/stapprobes.3stap.html stapprobes man page] for the NON-DWARF and AUTO-DWARF probe types for what should still work, for example:

* kernel tracepoints: kernel.trace("*")
* user-space probes: process("...").function("...")  (for programs you build yourself with -g)
* user-space markers: process("...").mark("...")   (if they were configured with the ''<sys/sdt.h>'' markers)
* perfctr-based probes: perf.*
* non-dwarf kernel probes: kprobe.function("...") and nd_syscall.* tapset  (if a /boot/System.map* file is available, see below).

==Kernel rebuild==

You may consider to build a ''linux-custom'' package to run SystemTap, but rebuilding the original {{Pkg|linux}} package is easy and efficient.  See also [https://wiki.archlinux.org/index.php/Kernels/Compilation/Traditional].

===Prepare===
First, run {{ic|<nowiki>ABSROOT=. abs core/linux; cd core/linux</nowiki>}} to get the original kernel build files.
Then use {{ic|makepkg --verifysource}} to get the additional files. By performing the verification, you can safely '''skip''' the steps on "Update checksum".

===modify config===
Edit '''config''' (for 32-bit systems) or '''config.x86_64''' (for 64-bit systems), turn on these options:
* CONFIG_KPROBES=y
* CONFIG_KPROBES_SANITY_TEST=n
* CONFIG_KPROBE_EVENT=y
* CONFIG_NET_DCCPPROBE=m
* CONFIG_NET_SCTPPROBE=m
* CONFIG_NET_TCPPROBE=y
* CONFIG_DEBUG_INFO=y
* CONFIG_DEBUG_INFO_REDUCED=n
* CONFIG_X86_DECODER_SELFTEST=n
By default only ''CONFIG_DEBUG_INFO'' and ''CONFIG_DEBUG_INFO_REDUCED'' are not set.

With current core/linux (tested with 3.15.2) you can simply append these lines into config.[x86_64]:
{{hc|x86_64|
<nowiki>
echo '
CONFIG_DEBUG_INFO=y
CONFIG_DEBUG_INFO_REDUCED=n
' >> config.x86_64
</nowiki>
}}

''Note that if you want to put these lines into a self-maintained script, do not insert any space before CONFIG_* lines.''

===Update checksum===
''You can safely skip this step if you believe the source files are correct''.

Run {{ic|md5sum config[.x86_64]}} to get a new md5sum.

In '''PKGBUILD''' file, the {{ic|<nowiki>md5sums=('sum-of-first' ... 'sum-of-last')</nowiki>}} has the same order with
{{ic|<nowiki>source=('first-source' ... 'last-source')</nowiki>}}, put your new md5sum in the right place.

===Build and Install===
Optional: It is recommended to set {{ic|<nowiki>MAKEFLAGS="-j16"</nowiki>}} in {{ic|/etc/makepkg.conf}} to speed up the compilation.

You will need about 12 GB disk space for this build. Consider using an in-memory tmpfs if you have large DRAM.
Run {{ic|makepkg}} or {{ic|makepkg --skipchecksums}} to compile, then simply {{ic|sudo pacman -U *.pkg.tar.gz}} to install the packages.
'''pacman''' will tell you '''reinstall''', and you should say y.

{{Pkg|linux}} and {{Pkg|linux-headers}} should be reinstalled, {{Pkg|linux-docs}} does not matter.

Via this method, external modules (e.g. {{Pkg|nvidia}} and {{Pkg|virtualbox}}) do not need to be rebuilt.

==Build custom kernel==
Please reference this [http://sourceware.org/git/?p=systemtap.git;a=blob_plain;f=README;hb=HEAD README]

==Troubleshooting==

=== Pass 4 fails when launching ===

If you have:

    /usr/share/systemtap/runtime/stat.c:214:2: error: 'cpu_possible_map' undeclared (first use in this function)

Try to install systemtap-git package

=== System.map is missing ===

You can recover it where you build your linux kernel with DEBUG_INFO enabled
    
    cp src/linux-3.6/System.map /boot/System.map-3.6.7-1-ARCH

Alternately,

    sudo cp /proc/kallsyms /boot/System.map-`uname -r`