When constraining the highest DDR address that U-Boot will use for its data & relocated self, we need to handle the common case in which a 32 bit system with 2GB DDR will have a zero gd->ram_top, due to the addition of 2GB (0x80000000) to the base address of kseg0 (also 0x80000000) which overflows & wraps to 0.
We originally had a check for this case, but it was lost in commit 78edb25729ce ("boston: Provide physical CONFIG_SYS_SDRAM_BASE") causing problems for the affected 32 bit systems.
Signed-off-by: Paul Burton paul.burton@mips.com Fixes: 78edb25729ce ("boston: Provide physical CONFIG_SYS_SDRAM_BASE") Cc: Daniel Schwierzeck daniel.schwierzeck@gmail.com
--- Feel free to fold this into 78edb25729ce ("boston: Provide physical CONFIG_SYS_SDRAM_BASE") if you prefer Daniel.
board/imgtec/boston/ddr.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/board/imgtec/boston/ddr.c b/board/imgtec/boston/ddr.c index 00428496bd..892bb1754c 100644 --- a/board/imgtec/boston/ddr.c +++ b/board/imgtec/boston/ddr.c @@ -26,6 +26,15 @@ int dram_init(void) ulong board_get_usable_ram_top(ulong total_size) { DECLARE_GLOBAL_DATA_PTR; + ulong max_top;
- return min_t(ulong, gd->ram_top, (ulong)phys_to_virt(SZ_256M)); + /* Limit memory use to the top of (c)kseg0 */ + max_top = (ulong)phys_to_virt(SZ_256M); + + if (gd->ram_top < (ulong)phys_to_virt(0)) { + /* >= 2GB RAM on a 32 bit system wrapped around to 0 */ + return max_top; + } + + return min_t(ulong, gd->ram_top, max_top); }