Use a template assembly file to generate the embedded MFS.

This uses the .incbin directive to pull in the MFS image contents.
Using assembly directly ensures that symbols can be defined with the
name and properties (such as .size) desired without having to rename
symbols, etc. via a second objcopy invocation.  Since it is compiled
by the C compiler driver, it also avoids the need for all of the
EMBEDFS* make variables.

Suggested by:	jrtc27
Reviewed by:	kib, markj
Obtained from:	CheriBSD
MFC after:	2 weeks
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D26781

1 files changed, 3 insertions, 18 deletions

diff --git a/sys/conf/kern.post.mk b/sys/conf/kern.post.mk
index c9dce0e9f2f2..7df67e24f445 100644
--- a/sys/conf/kern.post.mk
+++ b/sys/conf/kern.post.mk
@@ -457,24 +457,9 @@ vnode_if_typedef.h:
 
 .if ${MFS_IMAGE:Uno} != "no"
 .if empty(MD_ROOT_SIZE_CONFIGURED)
-# Generate an object file from the file system image to embed in the kernel
-# via linking. Make sure the contents are in the mfs section and rename the
-# start/end/size variables to __start_mfs, __stop_mfs, and mfs_size,
-# respectively.
-embedfs_${MFS_IMAGE:T:R}.o: ${MFS_IMAGE}
-	${OBJCOPY} --input-target binary \
-	    --output-target ${EMBEDFS_FORMAT.${MACHINE_ARCH}} \
-	    --binary-architecture ${EMBEDFS_ARCH.${MACHINE_ARCH}} \
-	    ${MFS_IMAGE} ${.TARGET}
-	${OBJCOPY} \
-	    --rename-section .data=mfs,contents,alloc,load,readonly,data \
-	    --redefine-sym \
-		_binary_${MFS_IMAGE:C,[^[:alnum:]],_,g}_size=__mfs_root_size \
-	    --redefine-sym \
-		_binary_${MFS_IMAGE:C,[^[:alnum:]],_,g}_start=mfs_root \
-	    --redefine-sym \
-		_binary_${MFS_IMAGE:C,[^[:alnum:]],_,g}_end=mfs_root_end \
-	    ${.TARGET}
+embedfs_${MFS_IMAGE:T:R}.o: ${MFS_IMAGE} $S/dev/md/embedfs.S
+	${CC} ${CFLAGS} ${ACFLAGS} -DMFS_IMAGE="${MFS_IMAGE}" -c \
+	    $S/dev/md/embedfs.S -o ${.TARGET}
 .endif
 .endif