Hi,
On 3/22/21 2:20 PM, Alexandru Gagniuc wrote:
A now removed comment promises to "limit SYSRAM usage to first 128 KB".
This would imply that only SYSRAM from 0x2ffc0000 - 0x2ffe0000 would be
used. This is not what happens at all.
First, SPL_MAX_SIZE is referenced from SPL_TEXT_BASE, which on all
existing configs is set to 0x2ffc2500, not SYSRAM_BASE (0x2ffc0000).
Some of it is in the first 128 KiB and some of it is in the second
128 KiB chunk of SYSRAM.
Second, SPL_MAX_SIZE, does not restrict the BSS size. While a valiant
attempt is made via SPL_BSS_MAX_SIZE, the value of 0x00100000 is much
larger than SYSRAM, and doesn't account for the non-BSS sections.
Because we're putting the .text and .bss in the same boat, the correct
way to limit them together is via SPL_MAX_FOOTPRINT. With the current
SPL_TEXT_BASE, we couldn't limit even a very basic SPL to the first
128 KiB, and there is no technical reason to do so. Because of this,
simply allow the SPL to use all SYSRAM.
Signed-off-by: Alexandru Gagniuc <[email protected]>
---
include/configs/stm32mp1.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/configs/stm32mp1.h b/include/configs/stm32mp1.h
index 56a70cb584..440efa1a55 100644
--- a/include/configs/stm32mp1.h
+++ b/include/configs/stm32mp1.h
@@ -50,12 +50,12 @@
/* SPL support */
#ifdef CONFIG_SPL
/* SPL use DDR */
-#define CONFIG_SPL_BSS_MAX_SIZE 0x00100000
#define CONFIG_SYS_SPL_MALLOC_START 0xC0300000
#define CONFIG_SYS_SPL_MALLOC_SIZE 0x01D00000
-/* limit SYSRAM usage to first 128 KB */
-#define CONFIG_SPL_MAX_SIZE 0x00020000
+/* Restrict SPL to fit within SYSRAM */
+#define STM32_SYSRAM_END (STM32_SYSRAM_BASE + STM32_SYSRAM_SIZE)
+#define CONFIG_SPL_MAX_FOOTPRINT (STM32_SYSRAM_END -
CONFIG_SPL_TEXT_BASE)
#define CONFIG_SPL_STACK (STM32_SYSRAM_BASE + \
STM32_SYSRAM_SIZE)
#endif /* #ifdef CONFIG_SPL */
Thanks for the analysis.
We don't revisit this part this the first STM32MP port on U-Boot
and CONFIG_SPL_MAX_FOOTPRINT is the correct way to limit the SPL size.
If I remember correctly, the 128KB limitation was only a attempt to reserved
enough SYSRAM for BSS + SPL stack located at CONFIG_SPL_STACK = end of
sysram.
Reviewed-by: Patrick Delaunay <[email protected]>
Thanks
Patrick
