On Thu, Jul 9, 2020 at 3:07 AM Bin Meng <bmeng...@gmail.com> wrote: > > 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.
This is a recurring problem, I have another patch for Oreboot to fix the latest breakage. > > 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. I don't really like this though. I would prefer that we don't encourage guest software to behave differently on QEMU. I don't think other upstream boards do this. Besides Oreboot setting up the clocks are there any other users of this? Alistair > > 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 > >