Re: [Qemu-devel] [PATCH] hw/arm/allwinner: Fix crash with -nodefaults -M cubieboard

[Peter Maydell]

On 18 August 2017 at 18:08, Thomas Huth <address@hidden> wrote:
> The allwinner-a10 device uses serial_hds[0] without checking whether
> it is available or not. So using the cubieboard with -nodefaults
> currently results in a segmentation fault. Fix it by adding a
> proper check here.
> And while we're at it, mark the device as "user_creatable = false"
> since this apparently can not directly be used by the users but has
> to be wired up in code instead.
>
> Signed-off-by: Thomas Huth <address@hidden>
> ---
>  hw/arm/allwinner-a10.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/hw/arm/allwinner-a10.c b/hw/arm/allwinner-a10.c
> index f62a9a3..e152566 100644
> --- a/hw/arm/allwinner-a10.c
> +++ b/hw/arm/allwinner-a10.c
> @@ -109,8 +109,10 @@ static void aw_a10_realize(DeviceState *dev, Error 
> **errp)
>      sysbus_connect_irq(SYS_BUS_DEVICE(&s->sata), 0, s->irq[56]);
>
>      /* FIXME use a qdev chardev prop instead of serial_hds[] */
> -    serial_mm_init(get_system_memory(), AW_A10_UART0_REG_BASE, 2, s->irq[1],
> -                   115200, serial_hds[0], DEVICE_NATIVE_ENDIAN);
> +    if (serial_hds[0]) {
> +        serial_mm_init(get_system_memory(), AW_A10_UART0_REG_BASE, 2, 
> s->irq[1],
> +                       115200, serial_hds[0], DEVICE_NATIVE_ENDIAN);
> +    }

This doesn't look like the right fix, because it means that
there won't be a UART device at that point in system memory
at all. What you want is for there to be a UART device there
but not connected to anything, ie serial_mm_init() should cope
with being passed a NULL Chardev*.

thanks
-- PMM