From: Bin Meng <bin.m...@windriver.com> The reset vector codes are subject to change, e.g.: with recent fw_dynamic type image support, it breaks oreboot again.
Add a subregion in the MROM, with the size of machine RAM stored, so that we can provide a reliable way for bootloader to detect whether it is running in QEMU. Signed-off-by: Bin Meng <bin.m...@windriver.com> --- Changes in v2: - correctly populate the value in little-endian hw/riscv/sifive_u.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c index 3413369..79519d4 100644 --- a/hw/riscv/sifive_u.c +++ b/hw/riscv/sifive_u.c @@ -88,6 +88,7 @@ static const struct MemmapEntry { #define OTP_SERIAL 1 #define GEM_REVISION 0x10070109 +#define MROM_RAMSIZE_OFFSET 0xf8 static void create_fdt(SiFiveUState *s, const struct MemmapEntry *memmap, uint64_t mem_size, const char *cmdline) @@ -496,6 +497,26 @@ static void sifive_u_machine_init(MachineState *machine) riscv_rom_copy_firmware_info(memmap[SIFIVE_U_MROM].base, memmap[SIFIVE_U_MROM].size, sizeof(reset_vec), kernel_entry); + + /* + * Tell guest the machine ram size at MROM_RAMSIZE_OFFSET. + * On real hardware, the 64-bit value from MROM_RAMSIZE_OFFSET is zero. + * QEMU aware bootloader (e.g.: oreboot, U-Boot) can check value stored + * here to determine whether it is running in QEMU. + */ + + uint32_t ram_size[2] = { + machine->ram_size, + ((uint64_t)(machine->ram_size)) >> 32 + }; + + /* copy in the ram size in little_endian byte order */ + for (i = 0; i < ARRAY_SIZE(ram_size); i++) { + ram_size[i] = cpu_to_le32(ram_size[i]); + } + rom_add_blob_fixed_as("mrom.ram_size", ram_size, sizeof(ram_size), + memmap[SIFIVE_U_MROM].base + MROM_RAMSIZE_OFFSET, + &address_space_memory); } static bool sifive_u_machine_get_start_in_flash(Object *obj, Error **errp) -- 2.7.4