Re: [PATCH 1/9] hw/hppa/machine: Allow up to 3840 MB total memory

[BALATON Zoltan]

On Thu, 4 Jan 2024, deller@kernel.org wrote:
> From: Helge Deller <deller@gmx.de>
>
> The physical hardware allows DIMMs of 4 MB size and above, allowing up
> to 3840 MB of memory, but is restricted by setup code to 3 GB.
> Increase the limit to allow up to the maximum amount of memory.
>
> Btw. the memory area from 0xf000.0000 to 0xffff.ffff is reserved by
> the architecture for firmware and I/O memory and can not be used for
> standard memory.
>
> Signed-off-by: Helge Deller <deller@gmx.de>
> Noticed-by: Nelson H. F. Beebe <beebe@math.utah.edu>
> Fixes: b7746b1194c8 ("hw/hppa/machine: Restrict the total memory size to 3GB")
> ---
> hw/hppa/machine.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/hw/hppa/machine.c b/hw/hppa/machine.c
> index c8da7c18d5..6181f4b747 100644
> --- a/hw/hppa/machine.c
> +++ b/hw/hppa/machine.c
> @@ -276,6 +276,7 @@ static TranslateFn 
> *machine_HP_common_init_cpus(MachineState *machine)
>     unsigned int smp_cpus = machine->smp.cpus;
>     TranslateFn *translate;
>     MemoryRegion *cpu_region;
> +    ram_addr_t ram_max;
>
>     /* Create CPUs.  */
>     for (unsigned int i = 0; i < smp_cpus; i++) {
> @@ -288,8 +289,10 @@ static TranslateFn 
> *machine_HP_common_init_cpus(MachineState *machine)
>      */
>     if (hppa_is_pa20(&cpu[0]->env)) {
>         translate = translate_pa20;
> +        ram_max = 0xf0000000;      /* 3.75 GB (limited by 32-bit firmware) */
>     } else {
>         translate = translate_pa10;
> +        ram_max = 0xf0000000;      /* 3.75 GB (32-bit CPU) */

If the value is the same what's the point of setting it here and not once 
above at definition? It is's only the different comment then you could 
have a comment saying "3.75 GB, limited by 32-bit firmware on 64 bit CPU" 
or similar there.

Regards,
BALATON Zoltan

>     }
>
>     for (unsigned int i = 0; i < smp_cpus; i++) {
> @@ -311,9 +314,9 @@ static TranslateFn 
> *machine_HP_common_init_cpus(MachineState *machine)
>                                 cpu_region);
>
>     /* Main memory region. */
> -    if (machine->ram_size > 3 * GiB) {
> -        error_report("RAM size is currently restricted to 3GB");
> -        exit(EXIT_FAILURE);
> +    if (machine->ram_size > ram_max) {
> +        info_report("Max RAM size limited to %ld MB", ram_max / MiB);
> +        machine->ram_size = ram_max;
>     }
>     memory_region_add_subregion_overlap(addr_space, 0, machine->ram, -1);
>
> --
> 2.43.0