On 11/15/2010 09:17 PM, Grant Likely wrote:
On Mon, Nov 15, 2010 at 10:06 PM, Dirk Brandewie
<dirk.brande...@gmail.com> wrote:
On 11/15/2010 08:41 PM, Grant Likely wrote:
On Mon, Nov 15, 2010 at 08:01:20PM -0800, dirk.brande...@gmail.com wrote:
From: Dirk Brandewie<dirk.brande...@gmail.com>
This patch adds support for linking device tree blobs into
vmlinux. The device tree blobs are placed in the init.data
section.
Signed-off-by: Dirk Brandewie<dirk.brande...@gmail.com>
---
include/asm-generic/vmlinux.lds.h | 19 +++++++++++++++++--
scripts/Makefile.lib | 17 +++++++++++++++++
2 files changed, 34 insertions(+), 2 deletions(-)
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
/* The actual configuration determine if the init/exit sections
* are handled as text/data or they can be discarded (which
@@ -146,6 +153,13 @@
#define TRACE_SYSCALLS()
#endif
+
+#define KERNEL_DTB() \
+ . = ALIGN(DTB_ALIGNMENT); \
+ VMLINUX_SYMBOL(__dtb_start) = .; \
+ *(.dtb.init.rodata) \
+ VMLINUX_SYMBOL(__dtb_end) = .;
+
/* .data section */
#define DATA_DATA \
*(.data) \
@@ -468,7 +482,8 @@
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..a8a4774 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -200,6 +200,23 @@ 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<asm-generic/vmlinux.lds.h>'> $@
+ @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'>> $@
+
+DTC = $(objtree)/scripts/dtc/dtc
+
+quiet_cmd_dtc = DTC $@
+ cmd_dtc = $(DTC) -O dtb -o $(obj)/$*.dtb -b 0 $(src)/$*.dts
Missing the %.dtb: %.dts rule, but otherwise looks okay. You will
need to make sure this doesn't break powerpc or microblaze when the
dts->dtb rule is added.
I have the rule
$(obj)/%.dtb: $(src)/%.dts
$(call if_changed,dtc)
in the arch/x86/kernel/Makefile to prevent this sneaking into other other
architectures.
This rule looks correct. PowerPC and Microblaze need to be modified
to use it. It should not be hard to do, give it a try. Worst case,
your first attempt is wrong and the rest of us fix it up. :-)
Hint: PowerPC currently puts the .dtb file in a different directory
from the source .dts file. It doesn't need to do it that way.
arch/powerpc/boot/Makefile will need to be modified.
I will give it a shot. The only real difference except for the directory
structures is powerpc and microblaze add padding to the dtb with the -p 1024
command line argument to dtc. Is the padding needed when the blob are linked
into vmlinux proper?
--Dirk
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