Hi Heinrich, On Wed, 27 Oct 2021 at 06:21, Heinrich Schuchardt <heinrich.schucha...@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 <s...@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 <s...@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