Re: [PATCH v9] mac_oldworld: Allow loading binary ROM image

[BALATON Zoltan via <qemu-devel@nongnu.org>]

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On Sat, 17 Oct 2020, Philippe Mathieu-Daudé wrote:
> +Alistair for loader
>
> On 10/17/20 5:47 PM, BALATON Zoltan via 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>
>> Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>> ---
>> v9: Revert change from v8, back to the same as v7 rebased on latest
>>
>>   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 05e46ee6fe..0117ae17f5 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)
>> @@ -100,6 +102,7 @@ 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;
>> @@ -128,24 +131,32 @@ 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);
>> +        /* Unfortunately, load_elf sign-extends reading elf32 */
>
> Maybe this is what translate_fn() is for?
>
> uint64_t oldworld_phys(void *opaque, uint64_t addr)
> {
>    return addr & UINT32_MAX;
> }
>
> Using as (untested):
>
>        bios_size = load_elf(filename, NULL, oldworld_phys, NULL,
>                             NULL, &bios_addr, NULL,
>                             NULL, 1, PPC_ELF_MACHINE, 0, 0);

Please don't come up with any more great ideas for this patch unless you 
also propose a replacement and test it. This one works and we could just 
get this in as it is until the real problem with load_elf is fixed at 
which point all this can be removed so no need to be more sophisticated as 
the simple cast I have. As you can see in the original discussion:

http://patchwork.ozlabs.org/project/qemu-devel/patch/c69a791c7cad1246f3f34b3993dee4f549b75aa2.1593456926.git.balaton@eik.bme.hu/

problem is really in include/hw/elf_ops.h this is just a work around for 
that as I did not want to break anything I can't test so I'd rather fix it 
up here and let you fix load_elf then drop this cast. But unless you can 
do that before the freeze please don't hold up this patch any more.

Regards,
BALATON Zoltan

>> +        bios_addr = (uint32_t)bios_addr;
>> +
>> +        if (bios_size <= 0) {
>> +            /* or load binary ROM image */
>> +            bios_size = load_image_targphys(filename, PROM_BASE, 
>> PROM_SIZE);
>> +            bios_addr = PROM_BASE;
>> +        }
>>           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);
>>       }
>> 
>
>
>