From 284c12d52d66d91a3c8aa5f7f25113fc22a7350c009270a4a515621e7f5bf55f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20Tesa=C5=99=C3=ADk?= <ptesarik@suse.com>
Date: Wed, 9 Nov 2011 17:36:07 +0000
Subject: [PATCH] - README.static: Explain why static linking of some libraries
 is   preferred.

OBS-URL: https://build.opensuse.org/package/show/Kernel:kdump/makedumpfile?expand=0&rev=53
---
 README.static        | 45 ++++++++++++++++++++++++++++++++++++++++++++
 makedumpfile.changes |  6 ++++++
 makedumpfile.spec    |  1 +
 3 files changed, 52 insertions(+)
 create mode 100644 README.static

diff --git a/README.static b/README.static
new file mode 100644
index 0000000..133f5ac
--- /dev/null
+++ b/README.static
@@ -0,0 +1,45 @@
+Q: Why is makedumpfile linked statically?
+
+A: To save space.
+
+Loner answer follows.
+
+The secondary kernel runs in a very constrained environment. It cannot use
+the whole RAM of the machine, simply because this is the data that should
+be saved. Instead, it uses a special portion of RAM that is reserved for
+that purpose in the primary kernel. Since this is memory that cannot be
+used by the primary kernel (it is basically dead unless there is a kernel
+crash, which should be a rare event), it is desirable to keep the size of
+the reserved memory as small as possible.
+
+One thing that takes up RAM in the secondary kernel is the root file
+system. Now, the makedumpfile binary is also run from this filesystem.
+Consequently, initrd must also include all the dynamic libraries that
+this binary links against. This can increase the size of the initrd
+considerably.
+
+However, we don't need most of that space, because makedumpfile uses only
+a fraction of all the code present in the dynamic libraries. In fact, when
+makedumpfile is the only user of those libraries in the secondary kernel
+environment, the other usual term for these libraries, "shared libraries",
+no longer matches reality. It is not shared with anything else in the
+system. On the other hand, some libraries are also used by other binaries
+in the initrd, so it makes sense to link to them dynamically.
+
+The following libraries are shared with other tools:
+
+  libdl
+  libz
+
+The following libraries are only used by makedumpfile, and thus should be
+linked statically:
+
+  libdw
+  libebl
+  libelf
+  libbz2
+  liblzma
+
+Static versions of some of the above libraries may not be available in the
+distro, so a build-time check is performed, and they fall back to linking
+dynamically if necessary.
diff --git a/makedumpfile.changes b/makedumpfile.changes
index db3631a..5e4d8de 100644
--- a/makedumpfile.changes
+++ b/makedumpfile.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Wed Nov  9 17:31:50 UTC 2011 - ptesarik@suse.cz
+
+- README.static: Explain why static linking of some libraries is
+  preferred.
+
 -------------------------------------------------------------------
 Thu Nov  3 07:48:12 UTC 2011 - cfarrell@suse.com
 
diff --git a/makedumpfile.spec b/makedumpfile.spec
index 5d005f3..a3e1e93 100644
--- a/makedumpfile.spec
+++ b/makedumpfile.spec
@@ -30,6 +30,7 @@ Summary:        Partial kernel dump
 Group:          System/Kernel
 Url:            https://sourceforge.net/projects/makedumpfile/
 Source:         %{name}-%{version}.tar.bz2
+Source1:        README.static
 Patch0:         %{name}-coptflags.diff
 Patch1:         %{name}-supports-3.0.patch
 BuildRoot:      %{_tmppath}/%{name}-%{version}-build