Hi Ilias, On Fri Sep 12, 2025 at 12:03 PM IST, Ilias Apalodimas wrote: > Hi Anshul, > > On Fri, 5 Sept 2025 at 11:19, Anshul Dalal <[email protected]> wrote: >> >> For armv8, U-Boot uses a static map defined as 'mem_map' for configuring >> the MMU as part of mmu_setup. >> >> But since the exact configuration of memory banks might not be known at >> build time, many platforms such as imx9, versal2 etc. utilize >> gd->bd->bi_dram to configure the static map at runtime. >> >> Therefore this patch adds a new API mem_map_fix_dram_banks that modifies >> the static map in a similar way. Allowing for anyone to map all dram >> banks by just passing the index to last entry in their mem_map and it's >> length. >> >> Signed-off-by: Anshul Dalal <[email protected]> >> --- >> arch/arm/cpu/armv8/cache_v8.c | 27 +++++++++++++++++++++++++++ >> arch/arm/include/asm/armv8/mmu.h | 10 ++++++++++ >> 2 files changed, 37 insertions(+) >> >> diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c >> index 6e662395a83..edb895da1f2 100644 >> --- a/arch/arm/cpu/armv8/cache_v8.c >> +++ b/arch/arm/cpu/armv8/cache_v8.c >> @@ -58,6 +58,33 @@ static int get_effective_el(void) >> return el; >> } >> >> +int mem_map_fix_dram_banks(unsigned int index, unsigned int len, u64 attrs) >> +{ >> + unsigned int i; >> + int ret = fdtdec_setup_memory_banksize(); >> + >> + if (ret) { >> + printf("%s: Failed to setup dram banks\n", __func__); >> + return ret; >> + } >> + >> + if (index + CONFIG_NR_DRAM_BANKS >= len) { >> + printf("%s: Not sufficient space in memory map\n", __func__); >> + return -ENOMEM; >> + } > > The length of the mem_map array is configured at compile time. > So this is going to fail for all existing boards unless someone > explicitly changes the size of their struct mm_region. > I think if we go down that path, we need to change the error message > as well and point them to the right direction > >> + >> + for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) { >> + mem_map[index].virt = gd->bd->bi_dram[i].start; >> + mem_map[index].phys = gd->bd->bi_dram[i].start; >> + mem_map[index].size = gd->bd->bi_dram[i].size; >> + mem_map[index].attrs = attrs; >> + index++; >> + } >> + >> + mem_map[index] = (const struct mm_region){ 0 }; > > Why do you need the const? > Can we do > memset(&mem_map[index], 0, sizeof(mem_map[index])); > instead? >
Yeah, we could do that instead. But it essentially achieves the same thing, right? Regards, Anshul
