docs: improve compressed core file documentation

In particular, document "zcat vpp_core.gz | dd conv=sparse of=vpp_core"

Type: docs

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I01b70492ced864b47847c2ef7bc1ea8eb0980ec3

diff --git a/docs/troubleshooting/reportingissues/reportingissues.rst b/docs/troubleshooting/reportingissues/reportingissues.rst
index 461bff4..9192e20 100644 (file)
--- a/docs/troubleshooting/reportingissues/reportingissues.rst
+++ b/docs/troubleshooting/reportingissues/reportingissues.rst
@@ -198,9 +198,16 @@ If you start VPP from systemd, you also need to edit
 /lib/systemd/system/vpp.service and uncomment the "LimitCORE=infinity"
 line before restarting VPP.
 
 /lib/systemd/system/vpp.service and uncomment the "LimitCORE=infinity"
 line before restarting VPP.
 

-Vpp core files often appear enormous. Gzip typically compresses them
-to manageable sizes. A multi-GByte corefile often compresses to 10-20
-Mbytes.
+Vpp core files often appear enormous, but they are invariably
+sparse. Gzip compresses them to manageable sizes. A multi-GByte
+corefile often compresses to 10-20 Mbytes.
+
+When decompressing a vpp core file, we suggest using "dd" as shown to
+create a sparse, uncompressed core file:
+
+.. code-block:: console
+
+   $ zcat vpp_core.gz | dd conv=sparse of=vpp_core

 
 Please remember to put compressed core files in accessible places.
 
 
 Please remember to put compressed core files in accessible places.
 


@@ -209,6 +216,9 @@ Make sure to leave the default stanza "... unix { ... full-coredump
 /etc/vpp/startup.conf, or to include it in the command line arguments
 passed by orchestration software.
 
 /etc/vpp/startup.conf, or to include it in the command line arguments
 passed by orchestration software.
 

+Core files from Private Images
+==============================
+

 Core files from private images require special handling. If it's
 necessary to go that route, copy the **exact** Debian packages (or
 RPMs) which correspond to the core file to the same public place as
 Core files from private images require special handling. If it's
 necessary to go that route, copy the **exact** Debian packages (or
 RPMs) which correspond to the core file to the same public place as


@@ -239,8 +249,8 @@ dramatically different binary artifacts. All it takes is a different
 toolchain version.
 
 
 toolchain version.
 
 

-Compressed Core Files
----------------------
+On-the-fly Core File Compression
+--------------------------------

 
 Depending on operational requirements, it's possible to compress
 corefiles as they are generated. Please note that it takes several
 
 Depending on operational requirements, it's possible to compress
 corefiles as they are generated. Please note that it takes several