Re: [Qemu-devel] GSoC mentor summit QEMU users session

[Fabien Chouteau <chouteau@adacore.com>]

On 31/10/2011 14:12, Peter Maydell wrote:
> On 29 October 2011 14:52, Alexander Graf <agraf@suse.de> wrote:
>> A lot of people seem to also have code that doesn't make sense
>> upstream, for example implementing a one-off device that only
>> really matters for their own devboard which nobody else owns.
>> For such cases, having a plugin framework would be handy. I
>> interestingly enough got into the same discussion on LinuxCon
>> with some QEMU downstreams.
> 
> If we get the qdev rework done then I think we're probably in
> a better position to have a plugin framework for devices. (There
> are some issues about API and ABI stability guarantees, of course.)
> 

Interesting, we have a "plug-in" implementation in our Qemu branch. It
allows a plug-ins to register io_areas, read and write callback, trigger
interrupts, etc...

Qemu provides this interface to the plug-in:

struct QemuPlugin_Emulator
{
    uint64_t (*get_time)(QemuPlugin_ClockType clock);


    uint32_t (*add_event)(uint64_t              expire_time,
                          QemuPlugin_ClockType  clock,
                          uint32_t              event_id,
                          EventCallback         event,
                          void                 *opaque);

    uint32_t (*remove_event)(QemuPlugin_ClockType clock,
                             uint32_t             event_id);

    uint32_t (*set_irq)(uint32_t line, uint32_t level);

    uint32_t (*dma_read)(void          *dest,
                         target_addr_t  addr,
                         int            size);

    uint32_t (*dma_write)(void          *src,
                          target_addr_t  addr,
                          int            size);

    uint32_t (*attach_device)(QemuPlugin_DeviceInfo *dev);

    uint32_t version;
};

and the plug-in provides this interface to Qemu:

typedef uint32_t io_read_fn(void *opaque, target_addr_t addr, uint32_t size);

typedef void     io_write_fn(void          *opaque,
                             target_addr_t  addr,
                             uint32_t       size,
                             uint32_t       val);

typedef void reset_fn(void *opaque);
typedef void init_fn(void *opaque);
typedef void exit_fn(void *opaque);

typedef struct QemuPlugin_DeviceInfo
{
    uint32_t version;

    uint32_t vendor_id;
    uint32_t device_id;
    char     name[NAME_LENGTH];
    char     desc[DESC_LENGTH];

    void *opaque;

    io_read_fn  *io_read;
    io_write_fn *io_write;

    reset_fn *pdevice_reset;
    init_fn  *pdevice_init;
    exit_fn  *pdevice_exit;

    uint32_t nr_iomem;
    struct QemuPlugin_IOMemory
    {
        target_addr_t base;
        target_addr_t size;
    } iomem[MAX_IOMEM];
} QemuPlugin_DeviceInfo;

-- 
Fabien Chouteau