Hi Heinrich,
On Wed, 27 Oct 2021 at 06:21, Heinrich Schuchardt heinrich.schuchardt@canonical.com wrote:
On 10/27/21 10:50, Ilias Apalodimas wrote:
Hi Simon
How does this patch related to the standard boot series? Shouldn't this be a completely separate patch?
Probably, but I lose track of all the branches in progress, particularly when things sit for a while.
Thanks /Ilias
On Sun, 24 Oct 2021 at 02:26, Simon Glass sjg@chromium.org wrote:
LTO (Link-Time Optimisation) is an very useful feature which can significantly reduce the size of U-Boot binaries. So far it has been made available for selected ARM boards and sandbox.
However, incremental builds are much slower when LTO is used. For example, an incremental build of sandbox takes 2.1 seconds on my machine, but 6.7 seconds with LTO enabled.
Add a LTO_BUILD=n parameter to the build, so it can be disabled during development if needed, for faster builds.
Add some documentation about LTO while we are here.
Signed-off-by: Simon Glass sjg@chromium.org
(no changes since v1)
Makefile | 18 +++++++++++++----- arch/arm/config.mk | 4 ++-- arch/arm/include/asm/global_data.h | 2 +- doc/build/gcc.rst | 17 +++++++++++++++++ 4 files changed, 33 insertions(+), 8 deletions(-)
diff --git a/Makefile b/Makefile index b79b2319ff6..7057723e046 100644 --- a/Makefile +++ b/Makefile @@ -434,6 +434,9 @@ KBUILD_CFLAGS += -fshort-wchar -fno-strict-aliasing KBUILD_AFLAGS := -D__ASSEMBLY__ KBUILD_LDFLAGS :=
+# Set this to "n" use of LTO for this build, e.g. LTO_BUILD=n +LTO_BUILD ?= y
This does not allow LTO_BUILD=y to enable LTO for CONFIG_LTO=n.
We should have something like
LTO_CONFIG ?= $CONFIG_LTO
The CONFIG indicates that LTO is supported, so if we want to do that, we could fix the problems with LTO for a board/arch and send a patch to enable it. I think we want it enabled by default.
[..]
Regards
Simon