Userland debug symbols directory

Fri Nov 5 20:45:24 UTC 2010

On (05/11/2010 15:14), Mark Johnston wrote:
> Hi all,
> 
> I have some tentative patches which add support for creating a separate
> directory containing all of the userland debugging symbols.
> 
> I posted about this a week or so ago:
> http://lists.freebsd.org/pipermail/freebsd-hackers/2010-October/033437.html
> 
> Some future work will involve finding out if any changes are necessary to
> support Clang/LLVM, and seeing whether there's any interest in adding
> support to the FreeBSD installer to install the debug symbols to a
> user-defined directory.
> 
> Note that DEBUG_FLAGS must be set somewhere when building world -
> adding WITH_DEBUG_SYMBOLS_DIR=yes to src.conf beforehand is sufficient,
> as it causes DEBUG_FLAGS+=-g to be set; building world with DEBUG_FLAGS=-g
> alone is also sufficient. If the binaries are built without debug symbols
> and one tries to use my new option, nothing happens, i.e., no new
> files/directories are created, unless specific programs explicitly
> build with -g somehow (see below).
Hi,

I like the idea a lot, but why not to leave symbol files in /usr/obj,
otherwise it creates a problem of mismatch between installed binaries
and stale symbol files. Kernel case is very different, it preserves
previous version during 'make installkernel' besides one would hardly
need symbols for all installed binaries. It's for developers only after
all. If there is a problem to be debugged one can always find binary
and corresponding symbols file under /usr/obj.

I find this feature to be particularly useful for shlib-compat ABI
compatibility checker:
http://marc.info/?l=freebsd-hackers&m=128861933016176&w=2

> My changes are below. There's a new file (stripbin.sh) which invokes
> objcopy(1) and strip(1). At the moment it's in usr/src, but it should
> probably go elsewhere... perhaps usr/src/tools? The other changes are to
> bsd.prog.mk, bsd.own.mk and the src.conf man page.
> 
> I've also noticed a few Makefiles that explicitly set DEBUG_FLAGS=-g
> or CFLAGS+=-g for some reason. They are in
> 
> usr.bin/tar/
> cddl/usr.bin/ctfconvert/
> cddl/usr.sbin/usr.sbin/lockstat/
> usr.sbin/wpa/wpa_supplicant/
> usr.sbin/wpa/hostapd/
> usr.sbin/bluetooth/bthidd/
> 
> I'm not sure if this is intentional.
> 
> Feedback and suggestions are extremely welcome. =)
> 
> Thanks,
> -Mark
> 
> diff --git a/stripbin.sh b/stripbin.sh
> new file mode 100755
> index 0000000..be2e9ad
> --- /dev/null
> +++ b/stripbin.sh
> @@ -0,0 +1,29 @@
> +#!/bin/sh
> +
> +# This script is invoked by install(1) on all binaries when installing world.
> +# It determines whether any debug info is present in the binary; if so, it
> +# will extract the debug symbols to $SYMBOLS_FULLPATH, strip the binary and
> +# add a link to the binary which points to the file containing the debugging 
> +# symbols.
> +
> +: ${READELFEXEC:=/usr/obj/usr/src/gnu/usr.bin/binutils/readelf/readelf}
> +: ${STRIPEXEC:=/usr/obj/usr/src/gnu/usr.bin/binutils/strip/strip}
> +: ${OBJCEXEC:=/usr/obj/usr/src/gnu/usr.bin/binutils/objcopy/objcopy}
> +: ${DIRNAMEEXEC:=/usr/obj/usr/src/usr.bin/dirname/dirname}
Did it survive make universe? Looks incorrect for me. At least you
should depend on binaries which are part of the build toolchain, and not
hard code paths.

I'd propose not to add any scripts and handle it within makefiles.

> +
> +SYMBOLS_FULLPATH="${SYMBOLS_DIR}`${DIRNAMEEXEC} ${1}`"
> +
> +case $1 in
> +/*INS@*)
> +	exit 0
> +	;;
> +esac
> +
> +# Make sure that some debug info is actually present.
> +[ -z `$READELFEXEC -wi $1` ] && exit 0
> +
> +mkdir -p $SYMBOLS_FULLPATH
> +
> +$STRIPEXEC --only-keep-debug -o ${SYMBOLS_DIR}${1}.symbols $1
> +$STRIPEXEC --strip-debug $1
> +$OBJCEXEC --add-gnu-debuglink=${SYMBOLS_DIR}${1}.symbols $1
> diff --git a/share/mk/bsd.prog.mk b/share/mk/bsd.prog.mk
> index 47b43ab..9809db0 100644
> --- a/share/mk/bsd.prog.mk
> +++ b/share/mk/bsd.prog.mk
> @@ -29,6 +29,12 @@ CFLAGS+=${CRUNCH_CFLAGS}
>  
>  .if !defined(DEBUG_FLAGS)
>  STRIP?=	-s
> +.else
> +
> +.if defined(STRIPSCRIPT)
> +STRIP?= -s
> +INSTALL:= /usr/bin/env SYMBOLS_DIR=${SYMBOLS_DIR} STRIPBIN=${STRIPSCRIPT} ${INSTALL}
> +.endif
>  .endif
>  
>  .if defined(NO_SHARED) && (${NO_SHARED} != "no" && ${NO_SHARED} != "NO")
> diff --git a/share/mk/bsd.own.mk b/share/mk/bsd.own.mk
> index 3aa832c..80b42ad 100644
> --- a/share/mk/bsd.own.mk
> +++ b/share/mk/bsd.own.mk
> @@ -541,6 +541,12 @@ MK_${vv:H}:=	${MK_${vv:T}}
>  .endif
>  .endfor
>  
> +.if defined(WITH_DEBUG_SYMBOLS_DIR)
> +DEBUG_FLAGS+=	-g
> +STRIPSCRIPT=	/usr/src/stripbin.sh
> +SYMBOLS_DIR?=	/usr/local/lib/debug
> +.endif
> +
>  .endif # !_WITHOUT_SRCCONF
>  
>  .endif	# !target(__<bsd.own.mk>__)
> diff --git a/share/man/man5/src.conf.5 b/share/man/man5/src.conf.5
> index 4f8f9a1..d787746 100644
> --- a/share/man/man5/src.conf.5
> +++ b/share/man/man5/src.conf.5
> @@ -283,6 +283,15 @@ Set to not build CVS.
>  Set to not build
>  .Xr g++ 1
>  and related libraries.
> +.It Va WITH_DEBUG_SYMBOLS_DIR
> +Set this to have userland debugging symbols placed in a separate directory.
> +By default, they will be placed in
> +.Pa /usr/local/lib/debug/ .
> +A different location can be specified by defining
> +.Va SYMBOLS_DIR
> +when running make installworld.
> +Define this variable before running make buildworld to ensure that
> +the userland binaries will be built with debug symbols in the first place.
>  .It Va WITHOUT_DICT
>  .\" from FreeBSD: stable/8/tools/build/options/WITHOUT_DICT 156932 2006-03-21 07:50:50Z ru
>  Set to not build the Webster dictionary files.
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