Re: [Qemu-devel] [PATCH] hw/m68k/mcf5208: Support loading of bios images

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Thomas,

On 1/29/19 11:19 PM, Thomas Huth wrote:
> The MCF5208EVB supports 2 MiB of flash at address 0. Add support
> for this memory region and some code to load the file that can
> be specified with the "-bios" command line option.
> This can be used for example to load U-Boot images for the
> MCF5208EVB (we still lack some features in the CPU emulation for
> this firmware, though, so it can not be run successfully yet).
> 
> Signed-off-by: Thomas Huth <huth@tuxfamily.org>
> ---
>  hw/m68k/mcf5208.c | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/m68k/mcf5208.c b/hw/m68k/mcf5208.c
> index 0f2245dd81..021194498d 100644
> --- a/hw/m68k/mcf5208.c
> +++ b/hw/m68k/mcf5208.c
> @@ -27,6 +27,8 @@
>  
>  #define SYS_FREQ 166666666
>  
> +#define ROM_SIZE 0x200000
> +
>  #define PCSR_EN         0x0001
>  #define PCSR_RLD        0x0002
>  #define PCSR_PIF        0x0004
> @@ -227,6 +229,7 @@ static void mcf5208evb_init(MachineState *machine)
>      hwaddr entry;
>      qemu_irq *pic;
>      MemoryRegion *address_space_mem = get_system_memory();
> +    MemoryRegion *rom = g_new(MemoryRegion, 1);
>      MemoryRegion *ram = g_new(MemoryRegion, 1);
>      MemoryRegion *sram = g_new(MemoryRegion, 1);
>  
> @@ -237,6 +240,10 @@ static void mcf5208evb_init(MachineState *machine)
>      env->vbr = 0;
>      /* TODO: Configure BARs.  */
>  
> +    /* ROM at 0x00000000 */
> +    memory_region_init_rom(rom, NULL, "mcf5208.rom", ROM_SIZE, &error_fatal);
> +    memory_region_add_subregion(address_space_mem, 0x0, rom);

I'd use 0x00000000 here as in the comment.

> +
>      /* DRAM at 0x40000000 */
>      memory_region_allocate_system_memory(ram, NULL, "mcf5208.ram", ram_size);
>      memory_region_add_subregion(address_space_mem, 0x40000000, ram);
> @@ -285,9 +292,29 @@ static void mcf5208evb_init(MachineState *machine)
>      /*  0xfc0a4000 GPIO.  */
>      /* 0xfc0a8000 SDRAM controller.  */
>  
> +    /* Load firmware */
> +    if (bios_name) {
> +        char *fn;
> +        uint8_t *ptr;
> +
> +        fn = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
> +        if (!fn) {
> +            error_report("Could not find ROM image '%s'", bios_name);
> +            exit(1);
> +        }
> +        if (load_image_targphys(fn, 0x0, ROM_SIZE) < 8) {
> +            error_report("Could not load ROM image '%s'", bios_name);
> +            exit(1);
> +        }
> +        g_free(fn);

Can you add a comment about the 3 next lines?
As this doesn't seem m68k specific but firmware specific, shouldn't you
magic check for the image loaded to be your particular firmware (if this
is possible) or check $pc is within sane range?

> +        ptr = rom_ptr(0x4, 4);
> +        assert(ptr != NULL);
> +        env->pc = ldl_p(ptr);
> +    }
> +
>      /* Load kernel.  */
>      if (!kernel_filename) {
> -        if (qtest_enabled()) {
> +        if (qtest_enabled() || bios_name) {
>              return;
>          }
>          error_report("Kernel image must be specified");
>