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author | Marek BehĂșn <marek.behun@nic.cz> | 2021-05-20 14:24:10 +0300 |
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committer | Tom Rini <trini@konsulko.com> | 2021-05-24 21:21:30 +0300 |
commit | 86c5e21013d5efd895de9905a19893b4403e4642 (patch) | |
tree | 826e54e219b261f6d282c5f42d126276bc5af191 /arch/arm/mach-exynos | |
parent | 82b63e95410ebca0bbfd343ce163299a44a2d932 (diff) | |
download | u-boot-86c5e21013d5efd895de9905a19893b4403e4642.tar.xz |
ARM: make gd a function call for LTO and set via set_gd()
On ARM, the gd pointer is stored in registers r9 / x18. For this the
-ffixed-r9 / -ffixed-x18 flag is used when compiling, but using global
register variables causes errors when building with LTO, and these
errors are very difficult to overcome.
Richard Biener says [1]:
Note that global register vars shouldn't be used with LTO and if they
are restricted to just a few compilation units the recommended fix is
to build those CUs without -flto.
We cannot do this for U-Boot since all CUs use -ffixed-reg flag.
It seems that with LTO we could in fact store the gd pointer differently
and gain performance or size benefit by allowing the compiler to use
r9 / x18. But this would need more work.
So for now, when building with LTO, go the clang way, and instead of
declaring gd a global register variable, we make it a function call via
macro.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68384
Signed-off-by: Marek BehĂșn <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'arch/arm/mach-exynos')
-rw-r--r-- | arch/arm/mach-exynos/spl_boot.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/mach-exynos/spl_boot.c b/arch/arm/mach-exynos/spl_boot.c index 27f0dac182..722449881a 100644 --- a/arch/arm/mach-exynos/spl_boot.c +++ b/arch/arm/mach-exynos/spl_boot.c @@ -279,7 +279,7 @@ void memzero(void *s, size_t n) */ static void setup_global_data(gd_t *gdp) { - gd = gdp; + set_gd(gdp); memzero((void *)gd, sizeof(gd_t)); gd->flags |= GD_FLG_RELOC; gd->baudrate = CONFIG_BAUDRATE; |