Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754135Ab0LFTC7 (ORCPT ); Mon, 6 Dec 2010 14:02:59 -0500 Received: from pfepa.post.tele.dk ([195.41.46.235]:50309 "EHLO pfepa.post.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751955Ab0LFTC6 (ORCPT ); Mon, 6 Dec 2010 14:02:58 -0500 Date: Mon, 6 Dec 2010 20:02:51 +0100 From: Sam Ravnborg To: dirk.brandewie@gmail.com Cc: linux-kernel@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, sodaville@linutronix.de, linuxppc-dev@lists.ozlabs.org, microblaze-uclinux@itee.uq.edu.au, linux-arch@vger.kernel.org, mmarek@suse.cz Subject: Re: [PATCH 1/4] of: Add support for linking device tree blobs into vmlinux Message-ID: <20101206190251.GB20882@merkur.ravnborg.org> References: <76a37fa459aeadce5d11db8a7cc044687a2e0e8c.1291656753.git.dirk.brandewie@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <76a37fa459aeadce5d11db8a7cc044687a2e0e8c.1291656753.git.dirk.brandewie@gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6351 Lines: 182 On Mon, Dec 06, 2010 at 09:35:59AM -0800, dirk.brandewie@gmail.com wrote: > From: Dirk Brandewie > > This patch adds support for linking device tree blob(s) into > vmlinux. Modifies asm-generic/vmlinux.lds.h to add linking > .dtb sections into vmlinux. To maintain compatiblity with the of/fdt > driver code platforms MUST copy the blob to a non-init memory location > before the kernel frees the .init.* sections in the 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. > > STRUCT_ALIGNMENT is defined in vmlinux.lds.h for use in the rule to > create wrapper objects for the dtb in Makefile.lib. The > STRUCT_ALIGN() macro in vmlinux.lds.h is modified to use the > STRUCT_ALIGNMENT definition. > > 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 > --- > Documentation/kbuild/makefiles.txt | 15 +++++++++++++++ > include/asm-generic/vmlinux.lds.h | 15 ++++++++++++--- > scripts/Makefile.lib | 21 ++++++++++++++++++++- > 3 files changed, 47 insertions(+), 4 deletions(-) > > diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt > index 0ef00bd..fc18bb1 100644 > --- a/Documentation/kbuild/makefiles.txt > +++ b/Documentation/kbuild/makefiles.txt > @@ -1136,6 +1136,21 @@ When kbuild executes, the following steps are followed (roughly): > resulting in the target file being recompiled for no > obvious reason. > > + dtc > + Create flattend device tree blob object suitable for linking > + into vmlinux. Device tree blobs linked into vmlinux are placed > + in an init section in the image. Platform code *must* copy the > + blob to non-init memory prior to calling unflatten_device_tree(). > + > + Example: > + #arch/x86/platform/ce4100/Makefile > + clean-files := *dtb.S > + > + DTC_FLAGS := -p 1024 > + obj-y += foo.dtb.o > + > + $(obj)/%.dtb: $(src)/%.dts > + $(call if_changed,dtc) When using "if_changed" you need to add your target to targets-y. And you need to specify FORCE as a prerequisite to force kbuild to use the if_changed logic. The purpose of if_changed is to check if the commandlien has changed and execute the command again also if the commandline has changed. The simpler variant is $(call cmd,dtc) where you do not check the command line and do not need FORCE. > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > index bd69d79..024d3b9 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -23,7 +23,7 @@ > * _etext = .; > * > * _sdata = .; > - * RO_DATA_SECTION(PAGE_SIZE) > +* RO_DATA_SECTION(PAGE_SIZE) > * RW_DATA_SECTION(...) > * _edata = .; > * Change seems wrong. > @@ -67,7 +67,8 @@ > * 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) > > /* The actual configuration determine if the init/exit sections > * are handled as text/data or they can be discarded (which > @@ -146,6 +147,13 @@ > #define TRACE_SYSCALLS() > #endif > > + > +#define KERNEL_DTB() \ > + STRUCT_ALIGN(); \ > + VMLINUX_SYMBOL(__dtb_start) = .; \ > + *(.dtb.init.rodata) \ > + VMLINUX_SYMBOL(__dtb_end) = .; > + > /* .data section */ > #define DATA_DATA \ > *(.data) \ > @@ -468,7 +476,8 @@ > MCOUNT_REC() \ > DEV_DISCARD(init.rodata) \ > CPU_DISCARD(init.rodata) \ > - MEM_DISCARD(init.rodata) > + MEM_DISCARD(init.rodata) \ > + KERNEL_DTB() > > #define INIT_TEXT \ > *(.init.text) \ > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index 4c72c11..937eabbb 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -200,7 +200,26 @@ quiet_cmd_gzip = GZIP $@ > cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -f -9 > $@) || \ > (rm -f $@ ; false) > > - > +# DTC > +# --------------------------------------------------------------------------- > + > +# Generate an assembly file to wrap the output of the device tree compiler > +$(obj)/%.dtb.S: $(obj)/%.dtb > + @echo '#include ' > $@ > + @echo '.section .dtb.init.rodata,"a"' >> $@ > + @echo '.balign STRUCT_ALIGNMENT' >> $@ > + @echo '.global __dtb_$(*F)_begin' >> $@ > + @echo '__dtb_$(*F)_begin:' >> $@ > + @echo '.incbin "$<" ' >> $@ > + @echo '__dtb_$(*F)_end:' >> $@ > + @echo '.global __dtb_$(*F)_end' >> $@ > + @echo '.balign STRUCT_ALIGNMENT' >> $@ > + If we really want this rule in Makefile.lib then at least make it less verbose, and more secure. Something like this: quiet_dt_S_dtb_cmd = DTB $@ dt_S_dtb_cmd = \ ( \ @echo '#include '; \ @echo '.section .dtb.init.rodata,"a"'; \ @echo '.balign STRUCT_ALIGNMENT'; \ echo '.global __dtb_$(*F)_begin'; \ echo '__dtb_$(*F)_begin:'; \ echo '.incbin "$<" '; \ echo '__dtb_$(*F)_end:'; \ echo '.global __dtb_$(*F)_end'; \ echo '.balign STRUCT_ALIGNMENT'; \ ) > $@ $(obj)/%.dtb.S: $(obj)/%.dtb $(call cmd,dt_S_dtb) > +DTC = $(objtree)/scripts/dtc/dtc If this is the only spot where we use DTC then drop the variable. > + > +quiet_cmd_dtc = DTC $@ > + cmd_dtc = $(DTC) -O dtb -o $@ -b 0 $(DTC_FLAGS) $< > +ooo What is the purpose of these "ooo"? A debugging left-over? Sam -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/