[yocto] live image types and qemu machines

Darren Hart dvhart at linux.intel.com
Fri Jun 15 09:36:12 PDT 2012 


On 06/15/2012 09:29 AM, Barros Pena, Belen wrote:
> It definitely helps: thanks!
> 
> From what you say the following selections impact the image types:
> machine, base image and distro.
> 
> I need to give this a bit of thought. I might be back with even more
> questions (I hope that's ok).

Of course :-)

Note that IMAGE_FSTYPES is just a variable like anything else in
bitbake, and can be overriden, appended to, reset, by a number of
mechanisms. The ones I mentioned are the most common, and I believe the
only ones relevant to this discussion.

--
Darren

> 
> Have a great weekend.
> 
> Belen
> 
> On 15/06/2012 17:16, "Darren Hart" <dvhart at linux.intel.com> wrote:
> 
>>
>>
>> On 06/15/2012 08:56 AM, Barros Pena, Belen wrote:
>>> I'll try to explain:
>>>
>>> Your answer to my question was that we should allow outputting live
>>> images
>>> when building qemu machines because it could be useful to run those live
>>> images in the emulator, but the emulator is not currently capable of
>>> running live images (although it probably will in the future).
>>>
>>> If I have understood correctly (and this is a big if), it probably makes
>>> no sense to allow people to select live image types when building qemu
>>> images because right now they can do nothing with them: I guess they
>>> cannot deploy them to hardware, and they cannot run them in the emulator
>>> either. I wouldn't allow them to combine qemu and live images on the
>>> basis
>>> that this might change in the future.
>>>
>>> The fact that the emulator cannot run live images also impacts the next
>>> steps we provide once the image has been built. If we allowed Hob users
>>> to
>>> build for a qemu machine selecting ext2 and iso as the image types:
>>>
>>> - if the emulator could run the iso image we would need to ask those
>>> users
>>> which image they would like to run (iso or ext2)
>>> - if the emulator could not run the iso image, we could run the emulator
>>> without asking them questions because the only file we could run is the
>>> ext2
>>>
>>> Sorry for the longwinded answer: I hope it makes sense.
>>>
>>> Having said all this, I am still very much struggling to understand the
>>> relationship between machines, base images and image types. This
>>> relationship should inform the way we design the Hob interface. In the
>>> existing settings dialog, you select image types independently of the
>>> machine and base image you are building. Your selections will apply to
>>> any
>>> machine-base image combinations you can create within Hob. I am still
>>> trying to work out if this design is appropriate.
>>>
>>> On one side, I hear there are file types that make no sense for certain
>>> machines. The main example I could think of was live images and qemu
>>> machines (hence my question). On the other side, Richard spoke about
>>> using
>>> the IMAGE_FSTYPES values as default values for each base image, which
>>> tells me there must also be a relationship between base images and image
>>> types.
>>>
>>> If anybody would like to volunteer to help me understand how machines,
>>> base images and image types relate to each other, please let me know.
>>> Any
>>> help would be much appreciated :)
>>
>> OK, let me take a stab at this.
>>
>> base image: The image recipe to build, this defines the content of the
>> image such as which packages are installed. For example:
>>  core-image-minimal
>>  core-image-base
>>  core-image-sato
>>
>> image type: The format of the resulting image. All of the base images
>> can be built as any of the image types, but the distro and machine
>> definitions define which are allowed for the specific machine.
>>  ext2
>>  ext3
>>  tar.gz
>>  cpio.gz
>>  hddimg
>>  vmdk
>>
>> machine: The definition of the hardware (or emulator) we are building
>> the image for. This defines things like architecture, compiler options,
>> as well as adding dependencies on packages which are required or
>> recommended, this extends the list of packages defined in the image
>> recipe. For example, core-image-sato will provide the EMGD graphics
>> drivers for the crownbay machine and the i915 drivers for the n450. The
>> machine definition also modifies the IMAGE_FSTYPES list as appropriate
>> for the hardware.
>>
>> distro: The distro definition, such as poky, poky-tiny, angstrom, etc.
>> sets various policies about how things are built. This can include
>> package format (rpm, deb. etc), image fstypes, and preferred packages
>> for various configurable features like the kernel, C library, init
>> system, etc. This also impacts the contents and format of the resulting
>> image.
>>
>> Richard's suggestion to build the dialog from the IMAGE_FSTYPES makes
>> sense as it will allow you to list ONLY the image types that are
>> buildable for the selected distro and machine.
>>
>> Does that help?
>>
>> --
>> Darren
>>
>>
>>>
>>> Thanks!
>>>
>>> Belen
>>>
>>> On 15/06/2012 15:46, "Darren Hart" <dvhart at linux.intel.com> wrote:
>>>
>>>> On 06/15/2012 07:39 AM, Barros Pena, Belen wrote:
>>>>> Thanks for clarifying this, Darren. I think right now we need to
>>>>> design
>>>>> for what the current emulator can do. When things change, we should
>>>>> remember to update Hob.
>>>>
>>>> You suggested that this had a significant impact on the dialog for
>>>> selecting images. I thought knowing that qemu+live should/will be a
>>>> support situation would prevent you having to redesign the dialog
>>>> later,
>>>> as well as other design decisions that might stem from the assumption
>>>> that live images were not supported under emulation.
>>>>
>>>> --
>>>> Darren
>>>>
>>>>>
>>>>> Belen
>>>>>
>>>>> On 15/06/2012 15:31, "Darren Hart" <dvhart at linux.intel.com> wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>> On 06/15/2012 06:04 AM, Barros Pena, Belen wrote:
>>>>>>> Sorry, Darren and Liming: I have one more question about this.
>>>>>>> Liming,
>>>>>>> correct me if I am wrong, but you mentioned that the only files that
>>>>>>> can
>>>>>>> be run on the qemu emulator are ext2 and ext3. But Darren's answer
>>>>>>> seems
>>>>>>> to suggest that you can also run hddimg and iso files in the qemu
>>>>>>> emulator.
>>>>>>>
>>>>>>> Is this correct, or am I getting totally confused?
>>>>>>
>>>>>>
>>>>>> With the current implementation of the runqemu command and the
>>>>>> current
>>>>>> configuration of the qemu hardware, this is true. However, this will
>>>>>> change in the future as people have run into this and asked for
>>>>>> enhancements to allow it.
>>>>>>
>>>>>> --
>>>>>> Darren
>>>>>>
>>>>>>>
>>>>>>> Thanks!!
>>>>>>>
>>>>>>> Belen
>>>>>>>
>>>>>>> On 15/06/2012 10:33, "Barros Pena, Belen"
>>>>>>> <belen.barros.pena at intel.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Thanks Darren and Liming.
>>>>>>>>
>>>>>>>> It sounds like we should keep things as they are, and that we'll
>>>>>>>> need a
>>>>>>>> screen that gives you options to both run and deploy an image when
>>>>>>>> you
>>>>>>>> have built for qemu selecting image types ext2 or ext3 and live.
>>>>>>>>
>>>>>>>> Belen
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 14/06/2012 22:13, "Darren Hart" <dvhart at linux.intel.com> wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 06/14/2012 08:09 AM, Barros Pena, Belen wrote:
>>>>>>>>>> Hi all,
>>>>>>>>>>
>>>>>>>>>> The current Hob allows you to build images for a qemu machine
>>>>>>>>>> selecting
>>>>>>>>>> 'live' as your image type. To me (with my pitiful knowledge) this
>>>>>>>>>> doesn't
>>>>>>>>>> make much sense: would I want to deploy an image built for a
>>>>>>>>>> virtualisation environment in a real piece of hardware?
>>>>>>>>>>
>>>>>>>>>> So here goes a question: should we allow Hob users, who are
>>>>>>>>>> mainly
>>>>>>>>>> people
>>>>>>>>>> new to the Yocto project, to select the 'live' image type when
>>>>>>>>>> building
>>>>>>>>>> images for qemu machines?
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> In my opinion: YES. The reason is that this allows you to test the
>>>>>>>>> live
>>>>>>>>> image format and the boot mechanism on virtualized hardware. This
>>>>>>>>> is a
>>>>>>>>> valuable development tool.
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Darren
>>>>>>>>>
>>>>>>>>>> This might sound like a silly question, but it has a pretty big
>>>>>>>>>> impact
>>>>>>>>>> on
>>>>>>>>>> the Settings dialog and on the number of variations we need to
>>>>>>>>>> create
>>>>>>>>>> for
>>>>>>>>>> our 'Image details' screen, which appears after the build
>>>>>>>>>> finishes
>>>>>>>>>> and
>>>>>>>>>> displays logical next steps (like run the image or deploy your
>>>>>>>>>> image
>>>>>>>>>> to
>>>>>>>>>> external storage).
>>>>>>>>>>
>>>>>>>>>> Any help with this would be much appreciated.
>>>>>>>>>>
>>>>>>>>>> Thanks!
>>>>>>>>>>
>>>>>>>>>> Belen
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> ------------------------------------------------------------------
>>>>>>>>>> --
>>>>>>>>>> -
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>>>>>>>>>> _______________________________________________
>>>>>>>>>> yocto mailing list
>>>>>>>>>> yocto at yoctoproject.org
>>>>>>>>>> https://lists.yoctoproject.org/listinfo/yocto
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> -- 
>>>>>>>>> Darren Hart
>>>>>>>>> Intel Open Source Technology Center
>>>>>>>>> Yocto Project - Linux Kernel
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --------------------------------------------------------------------
>>>>>>>> -
>>>>>>>> Intel Corporation (UK) Limited
>>>>>>>> Registered No. 1134945 (England)
>>>>>>>> Registered Office: Pipers Way, Swindon SN3 1RJ
>>>>>>>> VAT No: 860 2173 47
>>>>>>>>
>>>>>>>> This e-mail and any attachments may contain confidential material
>>>>>>>> for
>>>>>>>> the sole use of the intended recipient(s). Any review or
>>>>>>>> distribution
>>>>>>>> by others is strictly prohibited. If you are not the intended
>>>>>>>> recipient, please contact the sender and delete all copies.
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> yocto mailing list
>>>>>>>> yocto at yoctoproject.org
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>>>>>>>
>>>>>>
>>>>>> -- 
>>>>>> Darren Hart
>>>>>> Intel Open Source Technology Center
>>>>>> Yocto Project - Linux Kernel
>>>>>>
>>>>>>
>>>>>
>>>>
>>>> -- 
>>>> Darren Hart
>>>> Intel Open Source Technology Center
>>>> Yocto Project - Linux Kernel
>>>>
>>>>
>>>
>>
>> -- 
>> Darren Hart
>> Intel Open Source Technology Center
>> Yocto Project - Linux Kernel
>>
>>
> 

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel

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