On 8/30/23 20:52, Tom Rini wrote:
On Tue, Aug 22, 2023 at 01:21:12PM +0530, Bhupesh Sharma wrote:
Ideally SYS_ICACHE_OFF and SYS_DCACHE_OFF should never be set for
ARM64 (ARMv8) platforms, as it makes booting u-boot slower on these
platforms.
However, if some platforms require ICACHE or DCACHE to be disabled
only for the smaller SPL stage, we should support such configurations
in u-boot as well.
I am missing the reason why this change should be accepted.
Compile-tested for:
- qemu arm64
qemu doesn't model caches that's why I don't think it is relevant here.
- imx8
- stm32
and run-tested on:
- Qualcomm RB3 platform
Cc: Tom Rini <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: Peng Fan <[email protected]>
Signed-off-by: Bhupesh Sharma <[email protected]>
Reviewed-by: Tom Rini <[email protected]>
---
arch/arm/Kconfig | 2 ++
arch/arm/cpu/armv8/Makefile | 4 ++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 36ee1e9a3c..92bff715e3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -141,6 +141,7 @@ config THUMB2_KERNEL
config SYS_ICACHE_OFF
bool "Do not enable icache"
+ depends on !ARM64
help
Do not enable instruction cache in U-Boot.
@@ -153,6 +154,7 @@ config SPL_SYS_ICACHE_OFF
config SYS_DCACHE_OFF
bool "Do not enable dcache"
+ depends on !ARM64
help
Do not enable data cache in U-Boot.
diff --git a/arch/arm/cpu/armv8/Makefile b/arch/arm/cpu/armv8/Makefile
index bba4f570db..0d0c1728e4 100644
--- a/arch/arm/cpu/armv8/Makefile
+++ b/arch/arm/cpu/armv8/Makefile
@@ -5,13 +5,13 @@
extra-y := start.o
+obj-y += cache_v8.o
obj-y += cpu.o
ifndef CONFIG_$(SPL_TPL_)TIMER
obj-$(CONFIG_SYS_ARCH_TIMER) += generic_timer.o
endif
ifndef CONFIG_$(SPL_)SYS_DCACHE_OFF
-obj-y += cache_v8.o
-obj-y += cache.o
+obj-y += cache.o
endif
ifdef CONFIG_SPL_BUILD
obj-$(CONFIG_ARMV8_SPL_EXCEPTION_VECTORS) += exceptions.o
I'm adding Michal here because this changes the behavior on xilinx
platforms that had the icache off. I was under the impression that at
the levels U-Boot runs at on aarch64, we just couldn't have
icache/dcache off, but I guess that's wrong?
yes. We are using icache off for mini u-boot configurations for quite a long
time. I tried to find out any commit why we started to use it but didn't find
any record. But will ask team to retest that use cases to see if that is working
or not.
In our case we are using small full U-Boot not any SPL variant.
My biggest issue with the patch is that it is not clear what issue it is trying
to solve as I have mentioned above.
It just says that ideally icache/dcache should be on. If you want to enforce it
on your platform you can select it when that platform is selected and don't need
enforce it for other platforms.
Thanks,
Michal
