Re: [PATCH v5 01/11] mac_oldworld: Allow loading binary ROM image

[Mark Cave-Ayland]

On 16/06/2020 14:47, BALATON Zoltan wrote:

> The beige G3 Power Macintosh has a 4MB firmware ROM. Fix the size of
> the rom region and fall back to loading a binary image with -bios if
> loading ELF image failed. This allows testing emulation with a ROM
> image from real hardware as well as using an ELF OpenBIOS image.
> 
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> ---
> v4: use load address from ELF to check if ROM is too big
> 
>  hw/ppc/mac_oldworld.c | 29 ++++++++++++++++++++---------
>  1 file changed, 20 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/ppc/mac_oldworld.c b/hw/ppc/mac_oldworld.c
> index f8c204ead7..baf3da6f90 100644
> --- a/hw/ppc/mac_oldworld.c
> +++ b/hw/ppc/mac_oldworld.c
> @@ -59,6 +59,8 @@
>  #define NDRV_VGA_FILENAME "qemu_vga.ndrv"
>  
>  #define GRACKLE_BASE 0xfec00000
> +#define PROM_BASE 0xffc00000
> +#define PROM_SIZE (4 * MiB)
>  
>  static void fw_cfg_boot_set(void *opaque, const char *boot_device,
>                              Error **errp)
> @@ -99,6 +101,7 @@ static void ppc_heathrow_init(MachineState *machine)
>      SysBusDevice *s;
>      DeviceState *dev, *pic_dev;
>      BusState *adb_bus;
> +    uint64_t bios_addr;
>      int bios_size;
>      unsigned int smp_cpus = machine->smp.cpus;
>      uint16_t ppc_boot_device;
> @@ -127,24 +130,32 @@ static void ppc_heathrow_init(MachineState *machine)
>  
>      memory_region_add_subregion(sysmem, 0, machine->ram);
>  
> -    /* allocate and load BIOS */
> -    memory_region_init_rom(bios, NULL, "ppc_heathrow.bios", BIOS_SIZE,
> +    /* allocate and load firmware ROM */
> +    memory_region_init_rom(bios, NULL, "ppc_heathrow.bios", PROM_SIZE,
>                             &error_fatal);
> +    memory_region_add_subregion(sysmem, PROM_BASE, bios);
>  
> -    if (bios_name == NULL)
> +    if (!bios_name) {
>          bios_name = PROM_FILENAME;
> +    }
>      filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
> -    memory_region_add_subregion(sysmem, PROM_ADDR, bios);
> -
> -    /* Load OpenBIOS (ELF) */
>      if (filename) {
> -        bios_size = load_elf(filename, NULL, 0, NULL, NULL, NULL, NULL, NULL,
> -                             1, PPC_ELF_MACHINE, 0, 0);
> +        /* Load OpenBIOS (ELF) */
> +        bios_size = load_elf(filename, NULL, NULL, NULL, NULL, &bios_addr,
> +                             NULL, NULL, 1, PPC_ELF_MACHINE, 0, 0);
> +        if (bios_size <= 0) {
> +            /* or load binary ROM image */
> +            bios_size = load_image_targphys(filename, PROM_BASE, PROM_SIZE);
> +            bios_addr = PROM_BASE;
> +        } else {
> +            /* load_elf sets high 32 bits for some reason, strip those */
> +            bios_addr &= 0xffffffffULL;

This is certainly the approach I suggested, but this seems wrong - otherwise
load_elf() would be broken for quite a few use cases.

> +        }
>          g_free(filename);
>      } else {
>          bios_size = -1;
>      }
> -    if (bios_size < 0 || bios_size > BIOS_SIZE) {
> +    if (bios_size < 0 || bios_addr - PROM_BASE + bios_size > PROM_SIZE) {
>          error_report("could not load PowerPC bios '%s'", bios_name);
>          exit(1);
>      }

(goes and looks)

This is similar to how the SPARC32 loader works and it seems fine there:
https://git.qemu.org/?p=qemu.git;a=blob;f=hw/sparc/sun4m.c;h=ee52b5cbbcd22284384225c80ad50cdbd1415743;hb=HEAD#l721.
Looks like you might have the wrong addr parameter here?


ATB,

Mark.