On 10/19/2017 01:06 PM, Peter Maydell wrote:
> On 19 October 2017 at 11:04, Cédric Le Goater <c...@kaod.org> wrote:
>> Some legacy firmwares access unimplemented addresses on the Aspeed SoC
>> (old U-Boot code using variables in the bss when it shouldn't do).
>> Let's add a dummy ROM device to catch the invalid writes and support
>> new board without using the 'ignore_memory_transaction_failures' flags.
>>
>> Signed-off-by: Cédric Le Goater <c...@kaod.org>
>> ---
>> hw/arm/aspeed.c | 24 ++++++++++++++++++++++++
>> 1 file changed, 24 insertions(+)
>>
>> diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
>> index ab895ad490af..e44733153819 100644
>> --- a/hw/arm/aspeed.c
>> +++ b/hw/arm/aspeed.c
>> @@ -166,6 +166,19 @@ static void aspeed_board_init_flashes(AspeedSMCState
>> *s, const char *flashtype,
>> }
>> }
>>
>> +static void boot_rom_rw_flash_write(void *opaque, hwaddr offset, uint64_t
>> value,
>> + unsigned size)
>> +{
>> + qemu_log_mask(LOG_GUEST_ERROR,
>> + "%s: 0x%" HWADDR_PRIx " <- 0x%" PRIx64 " [%u]\n",
>> + __func__, offset, value, size);
>> +}
>> +
>> +static const MemoryRegionOps boot_rom_rw_flash_ops = {
>> + .write = boot_rom_rw_flash_write,
>> + .endianness = DEVICE_NATIVE_ENDIAN,
>> +};
>> +
>> static void aspeed_board_init(MachineState *machine,
>> const AspeedBoardConfig *cfg)
>> {
>> @@ -209,6 +222,7 @@ static void aspeed_board_init(MachineState *machine,
>> if (drive0) {
>> AspeedSMCFlash *fl = &bmc->soc.fmc.flashes[0];
>> MemoryRegion *boot_rom = g_new(MemoryRegion, 1);
>> + MemoryRegion *boot_rom_rw = g_new(MemoryRegion, 1);
>>
>> /*
>> * create a ROM region using the default mapping window size of
>> @@ -221,6 +235,16 @@ static void aspeed_board_init(MachineState *machine,
>> memory_region_add_subregion(get_system_memory(), FIRMWARE_ADDR,
>> boot_rom);
>> write_boot_rom(drive0, FIRMWARE_ADDR, fl->size, &error_abort);
>> +
>> + /*
>> + * Create a fake ROM region to track invalid writes done by
>> + * some legacy firmwares
>> + */
>> + memory_region_init_rom_device(boot_rom_rw, NULL,
>> &boot_rom_rw_flash_ops,
>> + NULL, "aspeed.boot_rom_rw", fl->size,
>> + &error_abort);
>> + memory_region_add_subregion_overlap(get_system_memory(),
>> FIRMWARE_ADDR,
>> + boot_rom_rw, 0);
>> }
>
> You're already (in some conditions) adding a memory region at this
> address -- you can see it just above. I think you probably want
> to be always creating this region in the same way, whether you
> need to do a write_boot_rom() to it or not, rather than creating
> two things at the same address.
ok. I didn't think that was possible. Let me try that.
Thanks,
C.
>
> I think that currently memory_region_init_rom() regions will
> MEMTX_DECODE_ERROR on attempts to write to them -- that's really
> a bug, which we might be able to fix, but for now you can do
> this with the init_rom_device() and a comment about why we
> can't just use memory_region_init_rom().
>
> thanks
> -- PMM
>
