Allow specification of virt board memory size via command line #18
Description
As of now we allocate 2Gib of memory by default, see https://github.com/foss-for-synopsys-dwc-arc-processors/qemu/blob/master/hw/arc/virt.c#L138:
#define VIRT_RAM_SIZE 0x80000000 ... /* Init system DDR */ system_ram = g_new(MemoryRegion, 1); memory_region_init_ram(system_ram, NULL, "arc.ram", VIRT_RAM_SIZE, &error_fatal);This allows simulated target to use the whole memory from 0x8000_0000 to the very end of 32-bit address space, which is convenient in some cases. But it also poses some limitations.
For example, even if one wants to run a simple "hello world" bare-metal application and 1 MiB of RAM is more than enough for that, you still cannot even start qemu on a machine with 2 GiB of RAM, see zephyrproject-rtos/sdk-ng#291.
And on the more powerful systems that leads to unnecessary overhead of resource usage.
The fix is as simple as:
diff --git a/hw/arc/sim-hs.c b/hw/arc/sim-hs.c index 7dbf23bd03..61f50118c0 100644 --- a/hw/arc/sim-hs.c +++ b/hw/arc/sim-hs.c @@ -25,7 +25,6 @@ #include "hw/sysbus.h" #define SIMHS_RAM_BASE 0x80000000 -#define SIMHS_RAM_SIZE 0x80000000 #define SIMHS_IO_BASE 0xf0000000 #define SIMHS_IO_SIZE 0x10000000 #define SIMHS_UART0_OFFSET 0x0 @@ -49,7 +48,7 @@ static void simhs_init(MachineState *machine) int n; boot_info.ram_start = SIMHS_RAM_BASE; - boot_info.ram_size = SIMHS_RAM_SIZE; + boot_info.ram_size = machine->ram_size; boot_info.kernel_filename = machine->kernel_filename; boot_info.kernel_cmdline = machine->kernel_cmdline; @@ -69,7 +68,7 @@ static void simhs_init(MachineState *machine) /* Init system DDR */ system_ram = g_new(MemoryRegion, 1); - memory_region_init_ram(system_ram, NULL, "arc.ram", SIMHS_RAM_SIZE, + memory_region_init_ram(system_ram, NULL, "arc.ram", machine->ram_size, &error_fatal); memory_region_add_subregion(system_memory, SIMHS_RAM_BASE, system_ram);