Re: [Qemu-devel] [PATCH] qemu-m68k: add support for interrupt masking/unmasking

[Stefan Weil <sw@weilnetz.de>]

Technically this implementation looks reasonable. I added some remarks 
below.

Am 22.03.2015 um 10:09 schrieb Waldemar Brodkorb:
> Fixes following problem, when trying to boot linux:
> qemu: hardware error: mcf_intc_write: Bad write offset 28
>
> CPU #0:
> D0 = 000000ff   A0 = 402ea5dc   F0 = 0000000000000000 (           0)
> D1 = 00000004   A1 = 402ea5e0   F1 = 0000000000000000 (           0)
> D2 = 00000040   A2 = 40040752   F2 = 0000000000000000 (           0)
> D3 = 00000000   A3 = 40040a98   F3 = 0000000000000000 (           0)
> D4 = 00000000   A4 = 400407b4   F4 = 0000000000000000 (           0)
> D5 = 00000000   A5 = 00000000   F5 = 0000000000000000 (           0)
> D6 = 00000000   A6 = 40195ff8   F6 = 0000000000000000 (           0)
> D7 = 00000000   A7 = 40195fd0   F7 = 0000000000000000 (           0)
> PC = 401b2058   SR = 2704 --Z-- FPRESULT =            0
> Aborted
>
> System started via:
> qemu-system-m68k -nographic -nographic -M mcf5208evb -cpu m5208 -kernel kernel
>
> Patch originally posted here:
> http://lists.busybox.net/pipermail/buildroot/2012-April/052585.html
>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Tested-by: Waldemar Brodkorb <wbx@openadk.org>
> Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
> ---
>   hw/m68k/mcf_intc.c |   18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
>
> diff --git a/hw/m68k/mcf_intc.c b/hw/m68k/mcf_intc.c
> index 621423c..1d161b1 100644
> --- a/hw/m68k/mcf_intc.c
> +++ b/hw/m68k/mcf_intc.c
> @@ -65,6 +65,10 @@ static uint64_t mcf_intc_read(void *opaque, hwaddr addr,
>           return (uint32_t)(s->ifr >> 32);
>       case 0x14:
>           return (uint32_t)s->ifr;
> +    /* Reading from SIMR and CIMR return 0 */
Maybe this comment is not needed if the following code is changed (see 
below).
> +    case 0x1c:

Add /* SIMR */ comment behind case statement like it was done for SWIACK.
Then either add a /* fall through */ comment or a return 0 (to satisfy 
static
code analyzers).

> +    case 0x1d:
Dto. for CIMR.
> +	return 0;
>       case 0xe0: /* SWIACK.  */
>           return s->active_vector;
>       case 0xe1: case 0xe2: case 0xe3: case 0xe4:
> @@ -102,6 +106,20 @@ static void mcf_intc_write(void *opaque, hwaddr addr,
>       case 0x0c:
>           s->imr = (s->imr & 0xffffffff00000000ull) | (uint32_t)val;
>           break;
> +    /* SIMR allows to easily mask interrupts */
> +    case 0x1c:
> +	if (val & 0x40)
> +		s->imr = ~0ull;
UINT64_MAX
> +	else
> +		s->imr |= (1 << (val & 0x3f));
The QEMU coding style requires {}.
> +	break;
> +    /* CIMR allows to easily unmask interrupts */
> +    case 0x1d:
> +	if (val & 0x40)
> +		s->imr = 0ull;
> +	else
> +		s->imr &= ~(1 << (val & 0x3f));
Dto.
> +	break;
>       default:
>           hw_error("mcf_intc_write: Bad write offset %d\n", offset);
>           break;