Re: [Qemu-devel] [PATCH v02] add 1394 bus support

[Peter Maydell]

On 19 April 2015 at 11:52,  <address@hidden> wrote:
> From: Itamar Tal <address@hidden>
>
> ---
>  default-configs/i386-softmmu.mak   |    1 +
>  default-configs/x86_64-softmmu.mak |    1 +
>  hw/1394/Makefile.objs              |    1 +
>  hw/1394/hcd-ohci.c                 | 1754 
> ++++++++++++++++++++++++++++++++++++
>  hw/1394/hcd-ohci.h                 |  147 +++
>  hw/Makefile.objs                   |    1 +
>  6 files changed, 1905 insertions(+)
>  create mode 100644 hw/1394/Makefile.objs
>  create mode 100644 hw/1394/hcd-ohci.c
>  create mode 100644 hw/1394/hcd-ohci.h

> +typedef union {
> +    uint32_t val;
> +    struct {
> +        uint32_t m:1;         /* = 0 */
> +        uint32_t initiated:1; /* = 1 for root node */
> +        uint32_t p2:2;        /* = 0 */
> +        uint32_t p1:2;        /* = 0 */
> +        uint32_t p0:2;        /* = 3, maybe 2 when "child" compared to root 
> */
> +        uint32_t pwr:3;       /* = 0 */
> +        uint32_t c:1;         /* = 1 when root */
> +        uint32_t del:2;       /* = 0? */
> +        uint32_t sp:2;        /* = 0? */
> +        uint32_t gap_cnt:6;   /* = 0? */
> +        uint32_t L:1;         /* = 1? maybe just when connected */
> +        uint32_t:1;           /* = 0 */
> +        uint32_t node_id:6;
> +        uint32_t type:2;      /* = 2 */
> +    };
> +} self_id_t;

> +        self_id_t sid;
> +
> +        sid.val = 0;
> +        sid.initiated = 1;
> +        sid.p0 = 2;
> +        sid.c = 1;
> +        sid.L = 1;
> +        sid.node_id = 0;
> +        sid.type = 2;
> +        dma_memory_write(&address_space_memory,
> +                         s->mmio.SelfIDBuffer + 4,
> +                         &sid.val, 4);

This assumes that the layout of bitfields is portable -- it is
not. You can't use a C bitfield to describe the layout of data
in guest memory. You need to get rid of all these structs with
bitfields and replace them with explicit AND/OR bit operations
on uint32_t types.

thanks
-- PMM