Install kernel debug data under /usr/lib/debug

This avoids needing a large boot partition / file system in order to
accommodate multiple kernels, and provides consistency with userland
debug. This also simplifies the process of moving kernel debug files
to a separate package and installing them on demand.

In addition, change kernel debug file extension to .debug, to match
userland debug files.

When using the supported kernel installation method the
/usr/lib/debug/boot/kernel directory will be renamed (to kernel.old)
as is done with /boot/kernel.

Developers wishing to maintain the historical behavior of installing
debug files in /boot/kernel/ can set KERN_DEBUGDIR="" in src.conf(5).

Reviewed by:	bdrewery, brooks, imp, markj
Relnotes:	yes
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D1006

UPDATING

@@ -31,6 +31,19 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 11.x IS SLOW:
 	disable the most expensive debugging functionality run
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20150925:
+	Kernel debug files have been moved to /usr/lib/debug/boot/kernel/,
+	and renamed from .symbols to .debug. This reduces the size requirements
+	on the boot partition or file system and provides consistency with
+	userland debug files.
+
+	When using the supported kernel installation method the
+	/usr/lib/debug/boot/kernel directory will be renamed (to kernel.old)
+	as is done with /boot/kernel.
+
+	Developers wishing to maintain the historical behavior of installing
+	debug files in /boot/kernel/ can set KERN_DEBUGDIR="" in src.conf(5).
+
 20150827:
 	The wireless drivers had undergone changes that remove the 'parent
 	interface' from the ifconfig -l output. The rc.d network scripts

etc/mtree/BSD.debug.dist

@@ -9,6 +9,8 @@
         bin
         ..
         boot
+            kernel
+            ..
         ..
         lib
             geom

share/man/man7/hier.7

@@ -383,7 +383,7 @@ shared libraries for compatibility
 a.out backward compatibility libraries
 .El
 .It Pa debug/
-standalone debug data for the base system libraries and binaries
+standalone debug data for the kernel and base system libraries and binaries
 .It Pa dtrace/
 DTrace library scripts
 .It Pa engines/

sys/conf/kern.post.mk

@@ -23,6 +23,11 @@ MKMODULESENV+=	CONF_CFLAGS="${CONF_CFLAGS}"
 MKMODULESENV+=	WITH_CTF="${WITH_CTF}"
 .endif
 
+# Allow overriding the kernel debug directory, so kernel and user debug may be
+# installed in different directories. Setting it to "" restores the historical
+# behavior of installing debug files in the kernel directory.
+KERN_DEBUGDIR?=	${DEBUGDIR}
+
 .MAIN: all
 
 .for target in all clean cleandepend cleandir clobber depend install \
@@ -101,11 +106,11 @@ modules-all modules-depend: modules-obj
 .if !defined(DEBUG)
 FULLKERNEL=	${KERNEL_KO}
 .else
-FULLKERNEL=	${KERNEL_KO}.debug
-${KERNEL_KO}: ${FULLKERNEL} ${KERNEL_KO}.symbols
-	${OBJCOPY} --strip-debug --add-gnu-debuglink=${KERNEL_KO}.symbols\
+FULLKERNEL=	${KERNEL_KO}.full
+${KERNEL_KO}: ${FULLKERNEL} ${KERNEL_KO}.debug
+	${OBJCOPY} --strip-debug --add-gnu-debuglink=${KERNEL_KO}.debug \
 	    ${FULLKERNEL} ${.TARGET}
-${KERNEL_KO}.symbols: ${FULLKERNEL}
+${KERNEL_KO}.debug: ${FULLKERNEL}
 	${OBJCOPY} --only-keep-debug ${FULLKERNEL} ${.TARGET}
 install.debug reinstall.debug: gdbinit
 	cd ${.CURDIR}; ${MAKE} ${.TARGET:R}
@@ -151,7 +156,7 @@ ${mfile:T:S/.m$/.h/}: ${mfile}
 
 kernel-clean:
 	rm -f *.o *.so *.So *.ko *.s eddep errs \
-	    ${FULLKERNEL} ${KERNEL_KO} ${KERNEL_KO}.symbols \
+	    ${FULLKERNEL} ${KERNEL_KO} ${KERNEL_KO}.debug \
 	    linterrs tags vers.c \
 	    vnode_if.c vnode_if.h vnode_if_newproto.h vnode_if_typedef.h \
 	    ${MFILES:T:S/.m$/.c/} ${MFILES:T:S/.m$/.h/} \
@@ -249,19 +254,26 @@ kernel-install:
 	if [ ! "`dirname "$$thiskernel"`" -ef ${DESTDIR}${KODIR} ] ; then \
 		chflags -R noschg ${DESTDIR}${KODIR} ; \
 		rm -rf ${DESTDIR}${KODIR} ; \
+		rm -rf ${DESTDIR}${KERN_DEBUGDIR}${KODIR} ; \
 	else \
 		if [ -d ${DESTDIR}${KODIR}.old ] ; then \
 			chflags -R noschg ${DESTDIR}${KODIR}.old ; \
 			rm -rf ${DESTDIR}${KODIR}.old ; \
 		fi ; \
 		mv ${DESTDIR}${KODIR} ${DESTDIR}${KODIR}.old ; \
+		if [ -n "${KERN_DEBUGDIR}" -a \
+		     -d ${DESTDIR}${KERN_DEBUGDIR}${KODIR} ]; then \
+			rm -rf ${DESTDIR}${KERN_DEBUGDIR}${KODIR}.old ; \
+			mv ${DESTDIR}${KERN_DEBUGDIR}${KODIR} ${DESTDIR}${KERN_DEBUGDIR}${KODIR}.old ; \
+		fi ; \
 		sysctl kern.bootfile=${DESTDIR}${KODIR}.old/"`basename "$$thiskernel"`" ; \
 	fi
 .endif
 	mkdir -p ${DESTDIR}${KODIR}
 	${INSTALL} -p -m 555 -o ${KMODOWN} -g ${KMODGRP} ${KERNEL_KO} ${DESTDIR}${KODIR}
 .if defined(DEBUG) && !defined(INSTALL_NODEBUG) && ${MK_KERNEL_SYMBOLS} != "no"
-	${INSTALL} -p -m 555 -o ${KMODOWN} -g ${KMODGRP} ${KERNEL_KO}.symbols ${DESTDIR}${KODIR}
+	mkdir -p ${DESTDIR}${KERN_DEBUGDIR}${KODIR}
+	${INSTALL} -p -m 555 -o ${KMODOWN} -g ${KMODGRP} ${KERNEL_KO}.debug ${DESTDIR}${KERN_DEBUGDIR}${KODIR}
 .endif
 .if defined(KERNEL_EXTRA_INSTALL)
 	${INSTALL} -p -m 555 -o ${KMODOWN} -g ${KMODGRP} ${KERNEL_EXTRA_INSTALL} ${DESTDIR}${KODIR}
@@ -273,7 +285,7 @@ kernel-reinstall:
 	@-chflags -R noschg ${DESTDIR}${KODIR}
 	${INSTALL} -p -m 555 -o ${KMODOWN} -g ${KMODGRP} ${KERNEL_KO} ${DESTDIR}${KODIR}
 .if defined(DEBUG) && !defined(INSTALL_NODEBUG) && ${MK_KERNEL_SYMBOLS} != "no"
-	${INSTALL} -p -m 555 -o ${KMODOWN} -g ${KMODGRP} ${KERNEL_KO}.symbols ${DESTDIR}${KODIR}
+	${INSTALL} -p -m 555 -o ${KMODOWN} -g ${KMODGRP} ${KERNEL_KO}.debug ${DESTDIR}${KERN_DEBUGDIR}${KODIR}
 .endif
 
 config.o env.o hints.o vers.o vnode_if.o:

sys/conf/kmod.mk

@@ -172,11 +172,11 @@ PROG=	${KMOD}.ko
 .if !defined(DEBUG_FLAGS)
 FULLPROG=	${PROG}
 .else
-FULLPROG=	${PROG}.debug
-${PROG}: ${FULLPROG} ${PROG}.symbols
-	${OBJCOPY} --strip-debug --add-gnu-debuglink=${PROG}.symbols\
+FULLPROG=	${PROG}.full
+${PROG}: ${FULLPROG} ${PROG}.debug
+	${OBJCOPY} --strip-debug --add-gnu-debuglink=${PROG}.debug \
 	    ${FULLPROG} ${.TARGET}
-${PROG}.symbols: ${FULLPROG}
+${PROG}.debug: ${FULLPROG}
 	${OBJCOPY} --only-keep-debug ${FULLPROG} ${.TARGET}
 .endif
 
@@ -266,7 +266,7 @@ ${_ILINKS}:
 CLEANFILES+= ${PROG} ${KMOD}.kld ${OBJS}
 
 .if defined(DEBUG_FLAGS)
-CLEANFILES+= ${FULLPROG} ${PROG}.symbols
+CLEANFILES+= ${FULLPROG} ${PROG}.debug
 .endif
 
 .if !target(install)
@@ -277,6 +277,7 @@ _INSTALLFLAGS:=	${_INSTALLFLAGS${ie}}
 .endfor
 
 .if !target(realinstall)
+KERN_DEBUGDIR?=	${DEBUGDIR}
 realinstall: _kmodinstall
 .ORDER: beforeinstall _kmodinstall
 _kmodinstall:
@@ -284,7 +285,7 @@ _kmodinstall:
 	    ${_INSTALLFLAGS} ${PROG} ${DESTDIR}${KMODDIR}
 .if defined(DEBUG_FLAGS) && !defined(INSTALL_NODEBUG) && ${MK_KERNEL_SYMBOLS} != "no"
 	${INSTALL} -o ${KMODOWN} -g ${KMODGRP} -m ${KMODMODE} \
-	    ${_INSTALLFLAGS} ${PROG}.symbols ${DESTDIR}${KMODDIR}
+	    ${_INSTALLFLAGS} ${PROG}.debug ${DESTDIR}${KERN_DEBUGDIR}${KMODDIR}
 .endif
 
 .include <bsd.links.mk>