On Thu, May 08, 2014 at 08:47:55AM +1000, Dave Chinner wrote: > On Wed, May 07, 2014 at 10:48:22AM -0400, Brian Foster wrote: > > Note that the Makefile structure between the core and libxfs/ subdir > > appears to be busted for module compiles. It attempts to create a > > libxfs.ko and doesn't appear to create any real link dependency between > > the logical modules: > > Ok, I hadn't tested that. I'll look into it. > > > ... > > WARNING: "__tracepoint_xfs_dir2_sf_create" [fs/xfs/libxfs/libxfs.ko] > > undefined! > > WARNING: "__tracepoint_xfs_da_root_join" [fs/xfs/libxfs/libxfs.ko] > > undefined! > > WARNING: "xfs_trans_mod_sb" [fs/xfs/libxfs/libxfs.ko] undefined! > > WARNING: "xfs_extent_busy_insert" [fs/xfs/libxfs/libxfs.ko] undefined! > > WARNING: "__tracepoint_xfs_dir2_sf_addname" [fs/xfs/libxfs/libxfs.ko] > > undefined! > > That tends to imply I didn't do the right thing with the tracing, > either. > > > CC fs/xfs/xfs.mod.o > > CC fs/xfs/libxfs/libxfs.mod.o > > LD [M] fs/xfs/xfs.ko > > LD [M] fs/xfs/libxfs/libxfs.ko > > > > I played with it a bit but didn't get anywhere without just pulling the > > source file dependency up into fs/xfs/Makefile. :/ > > I'll see what I can dig up. Well, I can make use of "lib-y" to get around the "libxfs is built as a module" problem: .... CC fs/xfs/libxfs/xfs_sb.o CC fs/xfs/libxfs/xfs_symlink_remote.o CC fs/xfs/libxfs/xfs_trans_resv.o AR fs/xfs/libxfs/lib.a but then there is the issue of adding it as a link flag to the xfs object itself. That involved a bit of a ld hack, but I have it compiling as a module now. Patch below. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx libxfs: fix modular build From: Dave Chinner <dchinner@xxxxxxxxxx> As reported by Brain Foster: Note that the Makefile structure between the core and libxfs/ subdir appears to be busted for module compiles. It attempts to create a libxfs.ko and doesn't appear to create any real link dependency between the logical modules: ... WARNING: "__tracepoint_xfs_dir2_sf_create" [fs/xfs/libxfs/libxfs.ko] undefined! WARNING: "__tracepoint_xfs_da_root_join" [fs/xfs/libxfs/libxfs.ko] undefined! WARNING: "xfs_trans_mod_sb" [fs/xfs/libxfs/libxfs.ko] undefined! WARNING: "xfs_extent_busy_insert" [fs/xfs/libxfs/libxfs.ko] undefined! WARNING: "__tracepoint_xfs_dir2_sf_addname" [fs/xfs/libxfs/libxfs.ko] undefined! CC fs/xfs/xfs.mod.o CC fs/xfs/libxfs/libxfs.mod.o LD [M] fs/xfs/xfs.ko LD [M] fs/xfs/libxfs/libxfs.ko Fix it by converting libxfs to be a static library, and hack the fs/xfs/xfs.o linker commands to include it directly and so completely avoid the need for a libxfs.ko module until we have sorted out all the circular dependency issues. Reported-by: Brian Foster <bfoster@xxxxxxxxxx> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> --- fs/xfs/Makefile | 22 +++++++++++++++++++--- fs/xfs/libxfs/Makefile | 12 +++++++----- 2 files changed, 26 insertions(+), 8 deletions(-) diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile index c520bff..726cfaa 100644 --- a/fs/xfs/Makefile +++ b/fs/xfs/Makefile @@ -20,10 +20,26 @@ ccflags-y += -I$(src) # needed for trace events ccflags-y += -I$(src)/libxfs # XXX: temporary! ccflags-y += -I$(src)/libxfs/include # XXX: temporary! -ccflags-$(CONFIG_XFS_DEBUG) += -g +# libxfs should inheret this as well. +subdir-ccflags-$(CONFIG_XFS_DEBUG) += -g -obj-$(CONFIG_XFS_FS) += xfs.o \ - libxfs/ +# When building as a module, we don't want a separate libxfs.ko, +# so we specifically have to link the libxfs.o object into the +# xfs.ko module. Hence we need to tell LD to do this appropriately. +#ldflags-y += -L$(obj)/libxfs -l:libxfs.o +# +# The use of --start-group without --endgroup here is a bit of a hack +# to avoid needing to use symbol exports and real modules. +# This works around the fact that ldflags-y is included on the linker command +# line before all the object files built in this directory, and hence +# it drops all the unreferenced symbols from libxfs. i.e. all the ones that +# that xfs.ko module actually requires. The lack of an "--end-group" varaible +# means LD considers all object files on the command line for recursive object +# searching and hence solves the specification order problem. +ldflags-y += --start-group $(obj)/libxfs/lib.a + +obj-$(CONFIG_XFS_FS) += libxfs/ \ + xfs.o # this one should be compiled first, as the tracing macros can easily blow up xfs-y += xfs_trace.o diff --git a/fs/xfs/libxfs/Makefile b/fs/xfs/libxfs/Makefile index e3de6df..b5f443b 100644 --- a/fs/xfs/libxfs/Makefile +++ b/fs/xfs/libxfs/Makefile @@ -8,11 +8,13 @@ ccflags-y += -I$(src)/.. ccflags-y += -I$(src)/include -Werror # needed for trace events -ccflags-$(CONFIG_XFS_DEBUG) += -g +# Use the lib-X directives rather than obj-X so that this doesn't get built as a +# module itself and have unresolvable circular dependencies with the xfs module. +# This means the xfs module needs to specifically link libxfs/lib.a because we +# are not adding fs/xfs/libxfs to the libs-y built-in library search +# directories. A bit hacky, but it seems to work as desired for modular builds. -obj-$(CONFIG_XFS_FS) += libxfs.o - -libxfs-y += xfs_alloc.o \ +lib-(CONFIG_XFS_FS) += xfs_alloc.o \ xfs_alloc_btree.o \ xfs_attr.o \ xfs_attr_leaf.o \ @@ -38,4 +40,4 @@ libxfs-y += xfs_alloc.o \ xfs_symlink_remote.o \ xfs_trans_resv.o -libxfs-$(CONFIG_XFS_RT) += xfs_rtbitmap.o +lib-$(CONFIG_XFS_RT) += xfs_rtbitmap.o _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
