From: Jeremy Compostella Date: Wed, 4 Feb 2026 02:42:36 +0000 (-0700) Subject: x86/coreboot: Exclude memory regions starting above 4GB X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=HEAD;p=thirdparty%2Fu-boot.git x86/coreboot: Exclude memory regions starting above 4GB This commit updates the RAM region filtering logic in board_get_usable_ram_top() to skip any memory regions whose start address is above 4GB. Previously, only the end address was capped at 4GB, but regions entirely above this threshold were still considered. Typically, the following memory map entries would cause board_get_usable_ram_top() to return 0x100000000, which is incorrect. start=00000000, end=00001000, type=16 start=00001000, end=000a0000, type=1 start=000a0000, end=000f6000, type=2 start=000f6000, end=000f7000, type=16 start=000f7000, end=00100000, type=2 start=00100000, end=6f170000, type=1 start=6f170000, end=70000000, type=16 start=70000000, end=80800000, type=2 start=e0000000, end=f8000000, type=2 start=fa000000, end=fc000000, type=2 start=fc800000, end=fc880000, type=2 start=fd800000, end=fe800000, type=2 start=feb00000, end=feb80000, type=2 start=fec00000, end=fed00000, type=2 start=fed20000, end=fed80000, type=2 start=feda1000, end=feda2000, type=2 start=fedc0000, end=fede0000, type=2 start=100000000, end=102400000, type=2 start=102400000, end=47f800000, type=1 start=4000000000, end=4020000000, type=2 By adding a check to continue the loop if the region's start address exceeds 0xffffffffULL, the function now properly ignores regions that are not usable in 32-bit address space. Signed-off-by: Jeremy Compostella --- diff --git a/arch/x86/cpu/coreboot/sdram.c b/arch/x86/cpu/coreboot/sdram.c index 013225f129a..cc1edd7badd 100644 --- a/arch/x86/cpu/coreboot/sdram.c +++ b/arch/x86/cpu/coreboot/sdram.c @@ -42,6 +42,8 @@ phys_addr_t board_get_usable_ram_top(phys_size_t total_size) continue; /* Filter memory over 4GB. */ + if (start > 0xffffffffULL) + continue; if (end > 0xffffffffULL) end = 0x100000000ULL; /* Skip this region if it's too small. */