On Fri, Sep 15, 2023 at 07:50:49PM +0200, Rasmus Villemoes wrote:
Currently, one can have both SYS_SPL_MALLOC=y and SPL_SYS_MALLOC_SIMPLE=y.
However, while the former does make board_init_r() in spl.c call mem_malloc_init(), that has no effect at all, because that just updates a few bookkeeping variables, but as the linker map shows, the latter setting has (as expected) caused most of dlmalloc.o to be garbage-collected. That is, those bookkeeping variables are not used for anything.
IOWs, with SYS_SPL_MALLOC=y and SPL_SYS_MALLOC_SIMPLE=y, the value of CONFIG_SYS_SPL_MALLOC_SIZE is irrelevant, and one still only has the small, SRAM-backed, malloc arena available.
Now I want to change that so that the mem_malloc_init() instead updates the gd->malloc* variables to point at the SDRAM area.
However, there's a small complication, namely when SPL_STACK_R=y is also in the mix. In that case, the "simple" malloc arena is indeed updated to point at the SDRAM area carved out of the new stack (see spl_relocate_stack_gd()). So that case works in the sense that one does get a "large" "simple" malloc arena (of size SPL_STACK_R_MALLOC_SIMPLE_LEN) - but CONFIG_SYS_SPL_MALLOC_SIZE is still irrelevant. Once I change the mem_malloc_init() logic, this would then break, because the gd->malloc* variables would be updated again. Also, it doesn't really make sense to allow the .config to essentially specify two different SDRAM-backed malloc arenas.
So since CONFIG_SYS_SPL_MALLOC and its dependent options are no-ops currently when SPL_STACK_R && SPL_SYS_MALLOC_SIMPLE, simply forbid that combination.
Simple grepping suggests that these boards/configs are affected, in that they become a tiny bit smaller, and the defconfig will need refreshing:
am62ax_evm_r5_defconfig am62x_evm_r5_defconfig am64x_evm_a53_defconfig am64x_evm_r5_defconfig am65x_evm_a53_defconfig am65x_hs_evm_a53_defconfig iot2050_defconfig j7200_evm_a72_defconfig j721e_evm_a72_defconfig j721s2_evm_a72_defconfig j721s2_evm_r5_defconfig verdin-am62_r5_defconfig
I've boot tested this on j721e and am65x evms, so it's likely true that all of these platforms are fine.