On 24/5/23 23:10, Mark Cave-Ayland wrote:
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-ayl...@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 8310670ec2..d12aeaa20e 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
@@ -452,6 +455,27 @@ static const MemoryRegionOps machine_id_ops = {
},
};
+static uint64_t ramio_read(void *opaque, hwaddr addr, unsigned size)
+{
Similar to empty_slot_init().
Personally I like to follow firmware detection using trace events here.
Maybe s/ramio/ram/.
+ return 0x0;
+}
static void q800_machine_init(MachineState *machine)
{
Q800MachineState *m = Q800_MACHINE(machine);
@@ -497,7 +521,11 @@ 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, NULL, &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);
Yes!
Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>
