Re: [Qemu-devel] [PATCH 1/3] hw/sd/pxa2xx_mmci: convert to SysBusDevice object

[Markus Armbruster <armbru@redhat.com>]

Peter Maydell <peter.maydell@linaro.org> writes:

> On 7 September 2015 at 17:57, Markus Armbruster <armbru@redhat.com> wrote:
>> Peter Maydell <peter.maydell@linaro.org> writes:
>>
>>> On 7 September 2015 at 17:40, Markus Armbruster <armbru@redhat.com> wrote:
>>>> Peter Maydell <peter.maydell@linaro.org> writes:
>>>>
>>>>> Convert the pxa2xx_mmci device to be a sysbus device.
>>>
>>>>> +static Property pxa2xx_mmci_properties[] = {
>>>>> +    /* Note: pointer property 'drive' may remain NULL, thus no need
>>>>> +     * for dc->cannot_instantiate_with_device_add_yet = true;
>>>>> +     * Unfortunately this can't be a DEFINE_PROP_DRIVE, because
>>>>> +     * setting a 'drive' property results in a call to blk_attach_dev()
>>>>> +     * attaching the BlockBackend to this device; that then means that
>>>>> +     * the call in sd_init() to blk_attach_dev_nofail() which tries to
>>>>> +     * attach the BlockBackend to the SD card object aborts.
>>>>> +     */
>>>>> +    DEFINE_PROP_PTR("drive", PXA2xxMMCIState, blk),
>>>>> +    DEFINE_PROP_END_OF_LIST(),
>>>>> +};
>>>>
>>>> As far as I can tell, this problem is an artifact of our interface to
>>>> the common sd-card code, namely sd_init().  sd_init() was made for the
>>>> pre-qdev world: it creates and completely initializes the common
>>>> SDState.
>>>>
>>>> In qdev, we do this in three separate steps: create, set properties,
>>>> realize.  Split up sd_init(), and the problem should go away.
>>>
>>> Yes, but I don't really want to gate QOMification of mmc
>>> controller devices on the more complicated problem of
>>> QOMifying sd.c itself, especially since we already have several
>>> QOMified mmc controllers...
>>
>> Is serial.c QOMified?  I don't think so, it's merely structured in a
>> QOM-friendly way: typedef SerialState, realize helper
>> serial_realize_core(), unrealize helper serial_exit_core().  If
>> SerialState had more properties, we'd also need a macro to define them.
>
> It looks like since we had this conversation the problem has been
> dealt with in commit 5ec911c30ff433 by simply turning the sd_init() call
> to blk_attach_dev_nofail() into a call to blk_attach_dev() which ignores
> its error return. So I should be able to do this with a DEFINE_PROP_DRIVE
> now I think...

Ignoring the error is intentional according to the comment, but why is
it appropriate?