ubuntu-phone team mailing list archive

[Alfonso Sanchez-Beato <alfonso.sanchez-beato@xxxxxxxxxxxxx>]

On Mon, Sep 14, 2015 at 1:55 PM, Simon Fels <simon.fels@xxxxxxxxxxxxx>
wrote:

> On 14.09.2015 13:12, John McAleely wrote:
>
>> I like the sound of multiarch for two reasons:
>>
>>   - It trivially guarantees compatibility for all the apps in the store
>> today
>>   - It allows us to make use of 64 bit whenever it is useful
>>
>> If we forgo the second advantage, we could just boot the kernel & android
>> container in 64 bit, and continue booting Ubuntu as a 32bit system. I've
>> documented this in a diagram here:
>>
>> https://wiki.ubuntu.com/Touch/ContainerArchitecture
>>
>> in the section: "mixed-containers, 32bit Ubuntu, 64bit Android". It seems
>> this would enable us to start using 64bit Android BSPs as a device
>> specific
>> feature of the device tarball, and then we can migrate Ubuntu to 64bit or
>> multiarch at a time of our own choosing (ie, we're not dictated to by the
>> availability of android BSPs).
>>
>> Unless there's any reason this scheme shouldn't work, I would like to
>> propose it as the initial way we use 64bit android BSPs.
>>
>
> That is fine for me.
>
> However as soon as we can't provide something we have to load through
> hybris and don't provide as a binder-accessible service on the container
> side we need a 64-bit version of libhybris and also 64 bit versions of
> those services on the Ubuntu side which are using those bits.
>
> Small example (not very likely to happen but to highlight what we might
> end up with):
>
> Android has a HAL lights module which is loaded by our powerd through
> libhybris. Means once the lights module is only available as 64 bit only
> (we only get a binary from the vendor, ...) we have to load it as 64 bit
> through hybris into powerd which brings us to the multiarch system with a
> 64 bit powerd.
>

One option we have in case we are very unlucky and one end *really* needs
to be 64 bits and the other end *really* needs to be 32 bits is to have a
daemon that would act as a proxy and that would communicate via DBus or
other IPC with the Ubuntu end (and would link with libhybris).

In fact most of the libhybris users are system daemons that use DBus as
communication mean, so we could install a 64 bit version of, say, powerd,
without affecting the rest of the system.


>
> I am not sure if we have those intersection points with the Android
> container documented but if not we should really do that to have an better
> overview for further decisions and possible requirements we put out for
> compatible Android BSPs.
>

Br,
Alfonso