[bitbake-devel] [PATCH 3/7] Hob: Make layers define in bblayers.conf as default

Wed Apr 4 00:23:57 UTC 2012

On 02/04/12 05:55, Richard Purdie wrote:
> On Sun, 2012-04-01 at 13:35 +0800, Xu, Dongxiao wrote:
>> On Sat, 2012-03-31 at 16:51 +0100, Richard Purdie wrote:
>>> On Sat, 2012-03-31 at 13:29 +0800, Xu, Dongxiao wrote:
>>>> On Sat, 2012-03-31 at 08:32 +0800, Xu, Dongxiao wrote:
>>>>> On Fri, 2012-03-30 at 09:10 -0700, Joshua Lock wrote:
>>>>>>
>>>>>> On 30/03/12 05:01, Dongxiao Xu wrote:
>>>>>>> For layers defined in bblayers.conf, we treat them as default layers
>>>>>>> and users are not allowed to remove them.
>>>>>>
>>>>>> Can you explain the rationale behind this change? I see what you're
>>>>>> doing but it's not entirely clear why.
>>>>>>
>>>>>> I think this is a bad idea. Early on in the design of Hob we decided we
>>>>>> didn't want configuration made for non-Hob builds to affect builds made
>>>>>> with Hob, and vice versa.
>>>>>
>>>>> The issue I am going to solve is that, with current local.conf
>>>>> (DISTRO="poky") and bblayers.conf (bblayers="meta meta-yocto"), we are
>>>>> not able to delete the meta-yocto layer in Hob since it will meet
>>>>> local.conf parsing error since it could not find where "poky" is
>>>>> defined.
>>>>>
>>>>> This patch is to set those layers define in bblayers.conf as default
>>>>> layers and they could not be removed. For example, in Yocto Project,
>>>>> "meta", "meta-yocto", and "meta-hob" are not removable. For pure OE-Core
>>>>> environment, "meta" and "meta-hob" are not removable.
>>>>>
>>>>
>>>> Just discussed with Josh on this problem.
>>>>
>>>> He suggested that meta-yocto should be still removable. If user met the
>>>> error after deleting the meta-yocto layer, he/she should change the
>>>> DISTRO setting in "Setting" dialog to "defaultsetup".
>>>>
>>>> Current code to handle the distro setting is:
>>>>
>>>>      def set_distro(self, distro):
>>>>          if distro != "defaultsetup":
>>>>              self.server.runCommand(["setVariable", "DISTRO", distro])
>>>>
>>>> Therefore even if user has selected defaultsetup, it will not set any
>>>> value to bitbake server, and then DISTRO ?= "poky" will take effect
>>>> while parsing local.conf.
>>>>
>>>> To make DISTRO ?= "poky" doesn't take effect, we need to change the code
>>>> to be:
>>>>
>>>>      def set_distro(self, distro):
>>>>          if distro == "defaultsetup":
>>>>              distro = ""
>>>>          self.server.runCommand(["setVariable", "DISTRO", distro])
>>>>
>>>> However Richard ever worried about this approach.
>>>> See:
>>>> http://lists.linuxtogo.org/pipermail/bitbake-devel/2012-March/002438.html
>>>>
>>>> In summary, there are two solutions now:
>>>>
>>>> 1) Set those layers defined in bblayers.conf as default, and don't allow
>>>> users to delete them, like this [PATCH 3/7] does.
>>>> 2) Use the empty string "" as the value of DISTRO variable for
>>>> "defaultsetup", and set this value before parsing configuration files,
>>>> making the DISTRO ?= "poky" in local.conf doesn't take effect.
>>>>
>>>> Welcome for comments on this issue.
>>>
>>> I'd be happy if you change the above code to do:
>>>
>>>          self.server.runCommand(["deleteVariable", "DISTRO"])
>>>
>>> which is subtly different but consistent with what we really want. I
>>> have no idea if we have a deleteVariable command but if we don't, we
>>> should add one.
>>
>> I ever tried this approach with the following patch, however it didn't
>> work. The setting of DISTRO ?= "poky" will still take effect.
>>
>> It seems that delVar(DISTRO) is different from setting DISTRO="".
>>
>>
>> diff --git a/bitbake/lib/bb/command.py b/bitbake/lib/bb/command.py
>> index 73aaca0..a7b41ce 100644
>> --- a/bitbake/lib/bb/command.py
>> +++ b/bitbake/lib/bb/command.py
>> @@ -160,6 +160,13 @@ class CommandsSync:
>>           value = params[1]
>>           command.cooker.configuration.data.setVar(varname, value)
>>
>> +    def delVariable(self, command, params):
>> +        """
>> +        Delete the variable in configuration.data
>> +        """
>> +        varname = params[0]
>> +        command.cooker.configuration.data.delVar(varname)
>> +
>>       def initCooker(self, command, params):
>>           """
>>           Init the cooker to initial state with nothing parsed
>> diff --git a/bitbake/lib/bb/ui/crumbs/hobeventhandler.py
>> b/bitbake/lib/bb/ui/crumbs/hobeventhandler.py
>> index 8909e01..d236a72 100644
>> --- a/bitbake/lib/bb/ui/crumbs/hobeventhandler.py
>> +++ b/bitbake/lib/bb/ui/crumbs/hobeventhandler.py
>> @@ -265,7 +265,9 @@ class HobHandler(gobject.GObject):
>>           self.server.runCommand(["setVariable", "IMAGE_FSTYPES",
>> image_fstypes])
>>
>>       def set_distro(self, distro):
>> -        if distro != "defaultsetup":
>> +        if distro == "defaultsetup":
>> +            self.server.runCommand(["delVariable", "DISTRO"])
>> +        else:
>>               self.server.runCommand(["setVariable", "DISTRO", distro])
>>
>>       def set_package_format(self, format):
>
> Thinking more about this, I think I can see a pattern in the issues I'm
> seeing patches for from you and Shane.
>
> I think you have things setup such that you do:
>
> a) Set variables
> b) Parse configuration
>
> And the problem is that if anywhere in the configuration, something like
> A = "B" happens, the value of A is overridden if you set it in A. This
> also would apply if you run delVar, then the code does a ?= since it
> will get reset.
>
> The trouble is you have to do this since you need to set MACHINE and
> DISTRO in advance.
>
> I'm starting to think you may have to have hob have its own empty
> "local.conf" which overrides the user provided one. You would parse the
> user's local.conf separately and extract any settings into hob as needed
> though (pass through all values except the ones you know need specific
> values from the UI).
>
> Its ugly but I can't see any better way to handle this situation that
> will make sense to the user and give the correct user experience. As I
> said to Shane elsewhere, we cannot force the local.conf file to be
> written in a certain way, just to suit the requirements of hob.

I wrote a quick hack this afternoon to do "settings import" from a users 
local.conf and whilst it is not a great solution it did spark some 
real-time conversation between Richard and I.

In an attempt at summary, it should be possible to have Hob:
* call bb.parse.handle() to load the user's settings from local.conf
* add appropriate values to the data store based on the parsed 
local.conf values and any appropriate hob settings
* parse as normal to fully populate the data store

Cheers,
Joshua
-- 
Joshua '贾詡' Lock
         Yocto Project "Johannes factotum"
         Intel Open Source Technology Centre