Re: [PATCH v4 2/8] Prioritize isar-apt repo over all others

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2018-02-12 11:11, Jan Kiszka wrote:
> On 2018-02-12 11:08, Alexander Smirnov wrote:
>> On 02/12/2018 12:41 PM, Jan Kiszka wrote:
>>> On 2018-02-12 10:33, Alexander Smirnov wrote:
>>>> On 02/11/2018 06:25 PM, Jan Kiszka wrote:
>>>>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>>>>
>>>>> This ensures that we can override packages from upstream Debian or
>>>>> other
>>>>> external sources with our self-built versions. We achieve this for now
>>>>> by asking multistrap to drop a preferences file for the buildchroot so
>>>>> that dependency installations use the right priority. For the image
>>>>> build, this does not work because all packages are pull during the
>>>>> bootstrap. Therefore, we set aptdefaultrelease to isar to ensure that
>>>>> our repo gets the higher priority.
>>>>>
>>>>
>>>> I'm not sure that I completely understand this. What is the use-case for
>>>> this? If you build your own copy of upstream package, this
>>>> prioritization could be resolved by specifying suffix to version.
>>>
>>> Simple example: custom kernel build of linux-cip
>>>
>>> This generates a package called linux-image-amd64 (for amd64 as target),
>>> and that may have a version < debian's kernel. Now, if we do not
>>> prioritize isar-apt over upstream, the upstream kernel is taken, even
>>> when you switched PREFERRED_PROVIDER (in fact, the build will break when
>>> that virtual package linux-cip is selected but can't be installed due to
>>> the version preference "newest").
>>
>> Ok, but why you can't name you kernel 'linux-cip-image-amd64'? Having
>> the same name as with original Debian one could be confusing.
>>
> 
> That is mandatory, in order to write packages that depend on THE kernel,
> instead of "my-custom-kernel-in-version-4.4.112".

To make it clearer, just look at the example-module case: The recipe can
build both against the distro as well as all custom kernels, without
touching it. And that is a pattern not limited to kernel<->module
relationships.

Jan

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