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

From: BALATON Zoltan <balaton@eik.bme.hu>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Cc: Howard Spoelstra <hsp.cat7@gmail.com>,
	qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
	David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH v5 01/11] mac_oldworld: Allow loading binary ROM image
Date: Fri, 26 Jun 2020 23:57:16 +0200 (CEST)	[thread overview]
Message-ID: <alpine.BSF.2.22.395.2006262354340.64843@zero.eik.bme.hu> (raw)
In-Reply-To: <38a2c38b-4f2b-2306-1a10-ec111364c1a4@ilande.co.uk>

On Fri, 26 Jun 2020, Mark Cave-Ayland wrote:
> 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?

I don't get this. Can you explain more please what is wrong and what's the 
proposed solution?

Regards,
BALATON Zoltan