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

[BALATON Zoltan]

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