Re: [PATCH 2/3] hw/hppa/machine: Do not limit the RAM to 3840MB

[Helge Deller]

On 08.01.20 19:14, Philippe Mathieu-Daudé wrote:
> The hardware expects DIMM slots of 1 or 2 GB, allowing up to
> 4 GB of memory. Accept the same amount of memory the hardware
> can deal with.
>
> The CPU doesn't have access to the RAM mapped in the
> [0xf0000000 - 0xf1000000] range because this is the PDC area
> (Processor Dependent Code) where the firmware is loaded.
> To keep this region with higher priority than the RAM, lower
> the RAM priority. The PDC will overlap it.
>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>  hw/hppa/machine.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/hw/hppa/machine.c b/hw/hppa/machine.c
> index 6775d879f8..d10c967d06 100644
> --- a/hw/hppa/machine.c
> +++ b/hw/hppa/machine.c
> @@ -90,16 +90,15 @@ static void machine_hppa_init(MachineState *machine)
>          g_free(name);
>      }
>
> -    /* Limit main memory. */
> -    if (ram_size > FIRMWARE_START) {
> -        machine->ram_size = ram_size = FIRMWARE_START;
> -    }
> -
>      /* Main memory region. */
> +    if (machine->ram_size > 4 * GiB) {
> +        error_report("RAM size of 4GB or more is not supported");
> +        exit(EXIT_FAILURE);
> +    }

My suggestion is to initially then limit it to max. 3GB, e.g.
> +    if (machine->ram_size > 3 * GiB) {
> +        error_report("RAM size of 3GB or more is not supported");
> +        exit(EXIT_FAILURE);

That way you don't need to work around the 4GB SeaBIOS limitation
in your other RFC patch.
So, people can start it with:
qemu-system-hppa -m 3g -serial stdio

Later then we can fix SeaBIOS, at least if 64bit support gets added later on.

>      ram_region = g_new(MemoryRegion, 1);
>      memory_region_allocate_system_memory(ram_region, OBJECT(machine),
>                                           "ram", ram_size);

^^^ here is still "ram_size". Do you need to change it?

> -    memory_region_add_subregion(addr_space, 0, ram_region);
> +    memory_region_add_subregion_overlap(addr_space, 0, ram_region, -1);
>
>      /* Init Dino (PCI host bus chip).  */
>      pci_bus = dino_init(addr_space, &rtc_irq, &serial_irq);
>

Helge