[Buildroot] Unstripped binaries for debugging with gdbserver

[Tzu-Jung Lee]

Hi Folks,

I'm debugging user programs with gdbserver.

Since binaries are stripped for the target, we need to use the
unstripped ones somewhere else.
The sysroot (staging) is the perfect candidate, and all we need to do
is to 'set sysroot' to staging in the gdb.

However, this requires the package to be installed in staging as well,
which is not the current default.

So I'm wondering does it make sense to turn on the "install staging'
by default when gdbserver is in used.


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commit 119ac6d18bca7f03ed70a63cc0f5ff694112bac0
Author: Tzu-Jung Lee <tjlee at ambarella.com>
Date:   Thu Jun 20 12:19:53 2013 +0800

    build: install staging if gdbserver is enabled.

    Change-Id: I7644813f06fc1b43744b04279afc84fc8c5efa58
    Signed-off-by: Tzu-Jung Lee <tjlee at ambarella.com>

diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
index 288fc94..f6d9297 100644
--- a/package/pkg-generic.mk
+++ b/package/pkg-generic.mk
@@ -308,7 +308,12 @@ $(2)_REDISTRIBUTE          ?= YES

 $(2)_DEPENDENCIES ?= $(filter-out $(1),$(patsubst
host-host-%,host-%,$(addprefix host-,$($(3)_DEPENDENCIES))))

+#ifdef BR2_PACKAGE_GDB_SERVER
+$(2)_INSTALL_STAGING           ?= YES
+#else
 $(2)_INSTALL_STAGING           ?= NO
+#endif
+
 $(2)_INSTALL_IMAGES            ?= NO
 $(2)_INSTALL_TARGET            ?= YES
 $(2)_DIR_PREFIX                        = $(if $(4),$(4),$(TOP_SRCDIR)/package)
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I also found a topic on FOSDEM 2013, which attempts to makes target/ a
subset of staging/
Any follow up on this?

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http://elinux.org/Buildroot:DeveloperDaysFOSDEM2013

Discussion

Copy target before creating images: the idea is to avoid the need for
creating idempotent scripts in e.g. post-build script. It does make
sense, because for the user it's a bit more difficult to make scripts
idempotent. Also it can be a step for hiding the "target" directory.
And it makes complete sense if we remove the "target" directory
completely and copy from staging instead.

The compelling reason to make target a subset of staging is that it is
much easier to do debugging: just "gdb staging/usr/bin/foo" and it
will have debug symbols and the paths to the source files.
Single install commands: FOO_INSTALL_CMDS. They get executed twice,
with DESTDIR set to the correct place (target or staging or host). The
POST_XXX_INSTALL_HOOKS would still be executed separately. But this
doesn't yet give us the situation that target and staging are the
same, but target just has some stuff removed.
Take it one step at the time: start with FOO_INSTALL_CMDS, we can see
how far we get.
Document that post-build script has to be idempotent (with an example).
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Regards,
Roy