Le 02/07/2023 à 17:48, Mark Cave-Ayland a écrit :
> MacOS attempts a series of writes and reads over the entire RAM area in order
> to determine the amount of RAM within the machine. Allow accesses to the
> entire RAM area ignoring writes and always reading zero for areas where there
> is no physical RAM installed to allow MacOS to detect the memory size without
> faulting.
>
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> ---
> hw/m68k/q800.c | 30 +++++++++++++++++++++++++++++-
> include/hw/m68k/q800.h | 1 +
> 2 files changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/hw/m68k/q800.c b/hw/m68k/q800.c
> index 081b95e9cf..3209309173 100644
> --- a/hw/m68k/q800.c
> +++ b/hw/m68k/q800.c
> @@ -86,6 +86,9 @@
>
> #define MAC_CLOCK 3686418
>
> +/* Size of whole RAM area */
> +#define RAM_SIZE 0x40000000
> +
> /*
> * Slot 0x9 is reserved for use by the in-built framebuffer whilst only
> * slots 0xc, 0xd and 0xe physically exist on the Quadra 800
> @@ -218,6 +221,27 @@ static const MemoryRegionOps machine_id_ops = {
> },
> };
>
> +static uint64_t ramio_read(void *opaque, hwaddr addr, unsigned size)
> +{
> + return 0x0;
> +}
> +
> +static void ramio_write(void *opaque, hwaddr addr, uint64_t val,
> + unsigned size)
> +{
> + return;
> +}
> +
> +static const MemoryRegionOps ramio_ops = {
> + .read = ramio_read,
> + .write = ramio_write,
> + .endianness = DEVICE_BIG_ENDIAN,
> + .valid = {
> + .min_access_size = 1,
> + .max_access_size = 4,
> + },
> +};
> +
> static void q800_machine_init(MachineState *machine)
> {
> Q800MachineState *m = Q800_MACHINE(machine);
> @@ -262,7 +286,11 @@ static void q800_machine_init(MachineState *machine)
> qemu_register_reset(main_cpu_reset, &m->cpu);
>
> /* RAM */
> - memory_region_add_subregion(get_system_memory(), 0, machine->ram);
> + memory_region_init_io(&m->ramio, OBJECT(machine), &ramio_ops, &m->ramio,
> + "ram", RAM_SIZE);
> + memory_region_add_subregion(get_system_memory(), 0x0, &m->ramio);
> +
> + memory_region_add_subregion(&m->ramio, 0, machine->ram);
>
> /*
> * Create container for all IO devices
> diff --git a/include/hw/m68k/q800.h b/include/hw/m68k/q800.h
> index 98097165d9..04e4e0bce3 100644
> --- a/include/hw/m68k/q800.h
> +++ b/include/hw/m68k/q800.h
> @@ -60,6 +60,7 @@ struct Q800MachineState {
> MacfbNubusState macfb;
> DJMEMCState djmemc;
> IOSBState iosb;
> + MemoryRegion ramio;
> MemoryRegion macio;
> MemoryRegion macio_alias;
> MemoryRegion machine_id;
Reviewed-by: Laurent Vivier <laurent@vivier.eu>