Hi
On 14.11.25 20:01, Grygorii Strashko wrote:
From: Grygorii Strashko <[email protected]>
Now all libfdt features are built-it unconditionally, but...
X86: The libfdt is used on x86 only to parse Hyperlaunch/dom0less Xen
nodes, so full libfdt is not needed in this case and minimal, RO
configuration can be used.
ARM - situation is more complicated:
1) ARM reads Host DT (fdt.c RO)
2) ARM reads passthrough DT (RO)
3) ARM generates dom0/hwdom DT from Host DT (there is a mix of WIP and SW APIs)
4) ARM generates domU DT (there is a mix of WIP and SW APIs)
4) With EFI enabled - ARM needs RW API and fdt_empty_tree
5) With CONFIG_OVERLAY_DTB - ARM needs RW and fdt_overlay API
Hence, add possibility for optimizing libfdt usage by introducing separate
Kconfig options for each libfdt feature and select them where needed.
Following libfdt modules are not used after this change:
Makefile.libfdt
fdt_addresses.c
fdt_strerror.c
fdt_check.c
Signed-off-by: Grygorii Strashko <[email protected]>
---
Not sure about using DOMAIN_BUILD_HELPERS for selecting
LIBFDT features, as DOMAIN_BUILD_HELPERS doesn't exactly
says that domain's DT will be generated when selected.
xen/arch/arm/Kconfig | 4 ++++
xen/common/Kconfig | 4 ++++
xen/common/libfdt/Kconfig | 14 ++++++++++++++
xen/common/libfdt/Makefile | 12 +++++++++---
4 files changed, 31 insertions(+), 3 deletions(-)
create mode 100644 xen/common/libfdt/Kconfig
Before continue Kconfig related discussion...
I've been thinking what if we use libfdt as a library (.a)?
We'd get the same result as linker can do optimization basing
on obj granularity while linking with library (.a).
OK. I've started experimenting - obvious choice is to use "lib-y" and
build system will do the rest. But in this case we'll lose ".init" and
libfdt will be built-in.
I've tried to preserve exiting behavior when libfdt is moved in ".init", but,
honestly got lost a bit in Xen build system.
Below diff is what I've came up with - probably no exactly right.
Does it make sense?
diff --git a/xen/Makefile b/xen/Makefile
index a4d53526bd0b..3fb77ab19853 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -464,6 +464,7 @@ ALL_OBJS-y += arch/$(SRCARCH)/built_in.o
ALL_OBJS-$(CONFIG_CRYPTO) += crypto/built_in.o
ALL_LIBS-y := lib/lib.a
+ALL_LIBS-$(CONFIG_LIBFDT) += common/libfdt/libfdt.a
include $(srctree)/arch/$(SRCARCH)/arch.mk
$(obj-y) $(obj-bin-y) $(extra-y) $(lib-y): _c_flags += $(cov-cflags-y)
diff --git a/xen/common/libfdt/Makefile b/xen/common/libfdt/Makefile
index 6ce679f98f47..e315252c88eb 100644
--- a/xen/common/libfdt/Makefile
+++ b/xen/common/libfdt/Makefile
@@ -1,21 +1,28 @@
-include $(src)/Makefile.libfdt
SECTIONS := text data $(SPECIAL_DATA_SECTIONS)
+obj-libfdt-y := fdt.o fdt_ro.o
+obj-libfdt-y += fdt_wip.o
+obj-libfdt-y += fdt_sw.o
+obj-libfdt-y += fdt_rw.o
+obj-libfdt-y += fdt_empty_tree.o
+obj-libfdt-y += fdt_overlay.o
+
# For CONFIG_OVERLAY_DTB, libfdt functionalities will be needed during runtime.
ifneq ($(CONFIG_OVERLAY_DTB),y)
OBJCOPYFLAGS := $(foreach s,$(SECTIONS),--rename-section .$(s)=.init.$(s))
-nocov-y += libfdt.o
+nocov-y += $(obj-libfdt-y)
endif
-obj-y += libfdt.o
-
CFLAGS-y += -I$(srctree)/include/xen/libfdt/
-$(obj)/libfdt.o: $(obj)/libfdt-temp.o FORCE
- $(call if_changed,objcopy)
+#lib-y += $(obj-libfdt-y)
-$(obj)/libfdt-temp.o: $(addprefix $(obj)/,$(LIBFDT_OBJS)) FORCE
- $(call if_changed,ld)
+$(obj)/libfdt-temp.a: $(addprefix $(obj)/,$(obj-libfdt-y)) FORCE
+ $(call if_changed,ar)
+
+$(obj)/libfdt.a: $(obj)/libfdt-temp.a FORCE
+ $(call if_changed,objcopy)
-targets += libfdt-temp.o $(LIBFDT_OBJS)
+extra-y += libfdt.a $(obj-libfdt-y)
+targets += libfdt-temp.a $(obj-libfdt-y)
--
Best regards,
-grygorii
