Re: [PATCH v1 1/3] hw/loongarch: Change FDT base addr to 2 MiB

[maobibo <maobibo@loongson.cn>]

Xiaojuan,

can you modify the tile like "Load FDT table into dram memory space"
rather than "change base addr to 2MiB" ?

regards
bibo,mao

在 2022/10/21 11:54, Xiaojuan Yang 写道:
> Change FDT base addr to 2 MiB in lowmem region. Since lowmem
> region starts from 0, FDT base address is located at 2 MiB to
> avoid NULL pointer access.
> 
> Signed-off-by: Xiaojuan Yang <yangxiaojuan@loongson.cn>
> ---
>  hw/loongarch/virt.c         | 18 +++++++++++-------
>  include/hw/loongarch/virt.h |  3 ---
>  2 files changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
> index 29df99727d..fe33e7e3e4 100644
> --- a/hw/loongarch/virt.c
> +++ b/hw/loongarch/virt.c
> @@ -159,7 +159,6 @@ static void fdt_add_pcie_node(const LoongArchMachineState *lams)
>                                   1, FDT_PCI_RANGE_MMIO, 2, base_mmio,
>                                   2, base_mmio, 2, size_mmio);
>      g_free(nodename);
> -    qemu_fdt_dumpdtb(ms->fdt, lams->fdt_size);
>  }
>  
>  static void fdt_add_irqchip_node(LoongArchMachineState *lams)
> @@ -689,6 +688,7 @@ static void loongarch_init(MachineState *machine)
>      MemoryRegion *address_space_mem = get_system_memory();
>      LoongArchMachineState *lams = LOONGARCH_MACHINE(machine);
>      int i;
> +    hwaddr fdt_base;
>  
>      if (!cpu_model) {
>          cpu_model = LOONGARCH_CPU_TYPE_NAME("la464");
> @@ -793,12 +793,16 @@ static void loongarch_init(MachineState *machine)
>      lams->machine_done.notify = virt_machine_done;
>      qemu_add_machine_init_done_notifier(&lams->machine_done);
>      fdt_add_pcie_node(lams);
> -
> -    /* load fdt */
> -    MemoryRegion *fdt_rom = g_new(MemoryRegion, 1);
> -    memory_region_init_rom(fdt_rom, NULL, "fdt", VIRT_FDT_SIZE, &error_fatal);
> -    memory_region_add_subregion(get_system_memory(), VIRT_FDT_BASE, fdt_rom);
> -    rom_add_blob_fixed("fdt", machine->fdt, lams->fdt_size, VIRT_FDT_BASE);
> +    /*
> +     * Since lowmem region starts from 0, FDT base address is located
> +     * at 2 MiB to avoid NULL pointer access.
> +     *
> +     * Put the FDT into the memory map as a ROM image: this will ensure
> +     * the FDT is copied again upon reset, even if addr points into RAM.
> +     */
> +    fdt_base = 2 * MiB;
> +    qemu_fdt_dumpdtb(machine->fdt, lams->fdt_size);
> +    rom_add_blob_fixed("fdt", machine->fdt, lams->fdt_size, fdt_base);
>  }
>  
>  bool loongarch_is_acpi_enabled(LoongArchMachineState *lams)
> diff --git a/include/hw/loongarch/virt.h b/include/hw/loongarch/virt.h
> index 09f1c88ee5..45c383f5a7 100644
> --- a/include/hw/loongarch/virt.h
> +++ b/include/hw/loongarch/virt.h
> @@ -28,9 +28,6 @@
>  #define VIRT_GED_MEM_ADDR       (VIRT_GED_EVT_ADDR + ACPI_GED_EVT_SEL_LEN)
>  #define VIRT_GED_REG_ADDR       (VIRT_GED_MEM_ADDR + MEMORY_HOTPLUG_IO_LEN)
>  
> -#define VIRT_FDT_BASE           0x1c400000
> -#define VIRT_FDT_SIZE           0x100000
> -
>  struct LoongArchMachineState {
>      /*< private >*/
>      MachineState parent_obj;