Re: [Qemu-devel] [PATCH v2] arm: add fw_cfg to "virt" board

[Peter Maydell]

On 30 November 2014 at 16:59, Laszlo Ersek <address@hidden> wrote:
> fw_cfg already supports exposure over MMIO (used in ppc/mac_newworld.c,
> ppc/mac_oldworld.c, sparc/sun4m.c); we can easily add it to the "virt"
> board.
>
> The mmio register block of fw_cfg is advertized in the device tree. As
> base address we pick 0x09020000, which conforms to the comment preceding
> "a15memmap": it falls in the miscellaneous device I/O range 128MB..256MB,
> and it is aligned at 64KB. The DTB properties follow the documentation in
> the Linux source file "Documentation/devicetree/bindings/arm/fw-cfg.txt".
>
> fw_cfg automatically exports a number of files to the guest; for example,
> "bootorder" (see fw_cfg_machine_reset()).
>
> Signed-off-by: Laszlo Ersek <address@hidden>
> ---
>
> Notes:
>     v2:
>     - use a single mmio region of size 0x1000
>     - set "compatible" property to "qemu,fw-cfg-mmio"
>
>  hw/arm/virt.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 314e55b..af794ea 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -68,6 +68,7 @@ enum {
>      VIRT_UART,
>      VIRT_MMIO,
>      VIRT_RTC,
> +    VIRT_FW_CFG,
>  };
>
>  typedef struct MemMapEntry {
> @@ -107,6 +108,7 @@ static const MemMapEntry a15memmap[] = {
>      [VIRT_GIC_CPU] =    { 0x08010000, 0x00010000 },
>      [VIRT_UART] =       { 0x09000000, 0x00001000 },
>      [VIRT_RTC] =        { 0x09010000, 0x00001000 },
> +    [VIRT_FW_CFG] =     { 0x09020000, 0x00001000 },

Where does this 0x1000 size come from? It's not the size
of the memory region the fw_cfg device exports, and it
means we'll end up telling the f/w in the dtb that the
accessible region is bigger than it really is.

Otherwise this patch looks good to me.

-- PMM