From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 17 Nov 2010 10:27:51 +0100 From: Sam Ravnborg To: dirk.brandewie@gmail.com, Michal Marek Subject: Re: [PATCH 1/5] of: Add support for linking device tree blobs into vmlinux Message-ID: <20101117092751.GA19781@merkur.ravnborg.org> References: <9129f0a21ea48fb2dcb89cea290e88f3e8c0d8a2.1289943240.git.dirk.brandewie@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <9129f0a21ea48fb2dcb89cea290e88f3e8c0d8a2.1289943240.git.dirk.brandewie@gmail.com> Cc: linux-arch@vger.kernel.org, linux-kbuild@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, devicetree-discuss@lists.ozlabs.org, linux-kernel@vger.kernel.org, sodaville@linutronix.de, microblaze-uclinux@itee.uq.edu.au, arjan@linux.intel.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Nov 16, 2010 at 02:41:36PM -0800, dirk.brandewie@gmail.com wrote: > From: Dirk Brandewie > > This patch adds support for linking device tree blobs into > vmlinux. Modifies asm-generic/vmlinux.lds.h to add linking > .dtb.init.rodata sections into the .init.data section of the vmlinux > image. Modifies scripts/Makefile.lib to add a kbuild command to > compile DTS files to device tree blobs and a rule to create objects to > wrap the blobs for linking. > > The DTB's are placed on 32 byte boundries to allow parsing the blob > with driver/of/fdt.c during early boot without having to copy the blob > to get the structure alignment GCC expects. > > A DTB is linked in by adding the DTB object to the list of objects to > be linked into vmlinux in the archtecture specific Makefile using > obj-y += foo.dtb.o > > Signed-off-by: Dirk Brandewie > --- > include/asm-generic/vmlinux.lds.h | 19 +++++++++++++++++-- > scripts/Makefile.lib | 20 ++++++++++++++++++++ > 2 files changed, 37 insertions(+), 2 deletions(-) When you touch Makefiles in scripts/* it is always a good idea to cc: kbuild maintainer on the patch - I have added Michal. Support functionality in Makefile.lib is documented in Documentation/kbuild/* - please add documentation there. > > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > index bd69d79..ea671e7 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -67,7 +67,14 @@ > * Align to a 32 byte boundary equal to the > * alignment gcc 4.5 uses for a struct > */ > -#define STRUCT_ALIGN() . = ALIGN(32) > +#define STRUCT_ALIGNMENT 32 > +#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT) > + > +/* Device tree blobs linked into the kernel need to have proper > + * structure alignment to be parsed by the flat device tree library > + * used in early boot > +*/ > +#define DTB_ALIGNMENT STRUCT_ALIGNMENT It has been discussed in another thread some time ago to move to a general 32 byte alignment for everything in vmlinux.lds.h So there is not much need for the specific DTB alignment. > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index 4c72c11..29db062 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -200,6 +200,26 @@ quiet_cmd_gzip = GZIP $@ > cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -f -9 > $@) || \ > (rm -f $@ ; false) > > +# DTC > +# --------------------------------------------------------------------------- > +$(obj)/%.dtb.S: $(obj)/%.dtb FORCE > + @echo '#include ' > $@ > + @echo '.section .dtb.init.rodata,"a"' >> $@ > + @echo '.balign DTB_ALIGNMENT' >> $@ > + @echo '.global __dtb_$(*F)_begin' >> $@ > + @echo '__dtb_$(*F)_begin:' >> $@ > + @echo '.incbin "$<" ' >> $@ > + @echo '__dtb_$(*F)_end:' >> $@ > + @echo '.global __dtb_$(*F)_end' >> $@ > + @echo '.balign DTB_ALIGNMENT' >> $@ This will be noisy during build. Please use proper macors to supress output. > + > +DTC = $(objtree)/scripts/dtc/dtc > + > +quiet_cmd_dtc = DTC $@ Please avoid tabs in the output - all other uses spaces. (There is a tab between DTC and $@) > + cmd_dtc = $(DTC) -O dtb -o $(obj)/$*.dtb -b 0 $(DTS_FLAGS) $(src)/dts/$*.dts Looks strange. How about: cmd_dtc = $(DTC) -O dtb -o $@ -b 0 $(DTS_FLAGS) $< Then you avoid the hardcoded path in the rule too. > + > +$(obj)/%.dtb: $(src)/dts/%.dts > + $(call if_changed,dtc) This snippet belong in the file that uses this. This is how we do for other rules like bzip etc. Sam