According to "Designing Cards and Drivers for the Macintosh Family" any attempt to access an unimplemented address location on Nubus generates a bus error. MacOS uses a custom bus error handler to detect empty Nubus slots, and with the current implementation assumes that all slots are occupied as the Nubus transactions never fail.
Switch nubus_slot_ops and nubus_super_slot_ops over to use {read,write}_with_attrs and hard-code them to return MEMTX_DECODE_ERROR so that unoccupied Nubus slots will generate the expected bus error. Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk> Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org> --- hw/nubus/nubus-bus.c | 34 ++++++++++++++++++---------------- 1 file changed, 18 insertions(+), 16 deletions(-) diff --git a/hw/nubus/nubus-bus.c b/hw/nubus/nubus-bus.c index 39182db065..a617459a4f 100644 --- a/hw/nubus/nubus-bus.c +++ b/hw/nubus/nubus-bus.c @@ -20,23 +20,23 @@ static NubusBus *nubus_find(void) return NUBUS_BUS(object_resolve_path_type("", TYPE_NUBUS_BUS, NULL)); } -static void nubus_slot_write(void *opaque, hwaddr addr, uint64_t val, - unsigned int size) +static MemTxResult nubus_slot_write(void *opaque, hwaddr addr, uint64_t val, + unsigned size, MemTxAttrs attrs) { - /* read only */ trace_nubus_slot_write(addr, val, size); + return MEMTX_DECODE_ERROR; } -static uint64_t nubus_slot_read(void *opaque, hwaddr addr, - unsigned int size) +static MemTxResult nubus_slot_read(void *opaque, hwaddr addr, uint64_t *data, + unsigned size, MemTxAttrs attrs) { trace_nubus_slot_read(addr, size); - return 0; + return MEMTX_DECODE_ERROR; } static const MemoryRegionOps nubus_slot_ops = { - .read = nubus_slot_read, - .write = nubus_slot_write, + .read_with_attrs = nubus_slot_read, + .write_with_attrs = nubus_slot_write, .endianness = DEVICE_BIG_ENDIAN, .valid = { .min_access_size = 1, @@ -44,23 +44,25 @@ static const MemoryRegionOps nubus_slot_ops = { }, }; -static void nubus_super_slot_write(void *opaque, hwaddr addr, uint64_t val, - unsigned int size) +static MemTxResult nubus_super_slot_write(void *opaque, hwaddr addr, + uint64_t val, unsigned size, + MemTxAttrs attrs) { - /* read only */ trace_nubus_super_slot_write(addr, val, size); + return MEMTX_DECODE_ERROR; } -static uint64_t nubus_super_slot_read(void *opaque, hwaddr addr, - unsigned int size) +static MemTxResult nubus_super_slot_read(void *opaque, hwaddr addr, + uint64_t *data, unsigned size, + MemTxAttrs attrs) { trace_nubus_super_slot_read(addr, size); - return 0; + return MEMTX_DECODE_ERROR; } static const MemoryRegionOps nubus_super_slot_ops = { - .read = nubus_super_slot_read, - .write = nubus_super_slot_write, + .read_with_attrs = nubus_super_slot_read, + .write_with_attrs = nubus_super_slot_write, .endianness = DEVICE_BIG_ENDIAN, .valid = { .min_access_size = 1, -- 2.20.1