Re: [PATCH] kernel: use oldnoconfig instead of yes '' | make oldconfig

[Bruce Ashfield <bruce.ashfield@windriver.com>]

On 14-01-29 08:10 AM, Alexandre Belloni wrote:
> Hi Bruce,
>
> Any news on that ?

Sorry, I hadn't intended for this to sit with no reply for this lenght
of time. I was tied up working with 3.13 and 3.14 yocto kerenls. I'm
now in a position to run some migration tests and will follow up with
the results asap.

Bruce

>
> On Tue, Jan 07, 2014 at 15:39:01 -0500, Bruce Ashfield wrote :
>> On 14-01-07 03:27 PM, Alexandre Belloni wrote:
>>> On 07/01/2014 16:32, Bruce Ashfield wrote:
>>>> On 14-01-07 09:18 AM, Alexandre Belloni wrote:
>>>>> When using a defconfig, using yes '' | make oldconfig may not result in
>>>>> the correct configuration being set. For example:
>>>>>
>>>>>    $ grep USB_ETH .config
>>>>>    CONFIG_USB_ETH=y
>>>>>    CONFIG_USB_ETH_RNDIS=y
>>>>>    CONFIG_USB_ETH_EEM=y
>>>>>    $ make savedefconfig
>>>>>    scripts/kconfig/conf --savedefconfig=defconfig Kconfig
>>>>>    $ cp defconfig .config
>>>>>    ‘defconfig’ -> ‘.config’
>>>>>    $ yes '' | make oldconfig
>>>>>    [...]
>>>>>    #
>>>>>    # configuration written to .config
>>>>>    #
>>>>>    $ grep USB_ETH .config
>>>>>    CONFIG_USB_ETH=m
>>>>>    CONFIG_USB_ETH_RNDIS=yThe enhancements in this release in comparison to previous releases are:
>>>>>    CONFIG_USB_ETH_EEM=y
>>>>>
>>>>> Using make olddefconfig solves that but we'll use oldnoconfig for
>>>>> backward compatibility with older kernels.
>>>>>
>>>>>    $ cp defconfig .config
>>>>>    ‘defconfig’ -> ‘.config’
>>>>>    $ make oldnoconfig
>>>>>    scripts/kconfig/conf --olddefconfig Kconfig
>>>>>    #
>>>>>    # configuration written to .config
>>>>>    #
>>>>>    $ grep USB_ETH .config
>>>>>    CONFIG_USB_ETH=y
>>>>>    CONFIG_USB_ETH_RNDIS=y
>>>>>    CONFIG_USB_ETH_EEM=y
>>>>>
>>>>> For more information, please refer to:
>>>>> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=fbe98bb9ed3dae23e320c6b113e35f129538d14a
>>>>>
>>>>
>>>> It was my understanding that this commit changed the Kconfig behaviour
>>>> to set the selected options to =y and prevent the menu choice from
>>>> "hiding" the options in a depedent choice menu. But maybe I'm remembering
>>>> wrong.
>>>>
>>>> The point being, that with that commit in place. Doesn't the behaviour
>>>> match what we want with yes and oldconfig ?
>>>>
>>>
>>> Nope, that commit is fixing the issue when using make <target>_defconfig
>>> or make olddefconfig. Note that using make menuconfig already had the
>>> correct behavior before that commit.
>>
>> right. I'm pretty familiar with that code, so I knew this worked.
>>
>>>
>>> As shown in my commit log, using yes '' | make oldconfig is still
>>> getting it wrong.
>>
>> But that was also my point. Since the target suggested in this
>> patch hasn't always existed (and hence has a kernel version binding),
>> why not use olddefconfig with this patch, and leave the functionality
>> closer to its existing behaviour ? We'd still have a kernel capability
>> binding, but we'd not have the =y converted to =m, and the default of
>> 'y' for new functionality would be maintained.
>>
>>>
>>>> .. I'll run some tests to confirm for myself, but I thought I'd throw
>>>> the question out as well. I don't typically use defconfigs, so I need
>>>> to do a bit of leg work.
>>>>
>>>
>>> Yeah, using a full .config doesn't trigger that behavior.
>>
>> I don't use those either :) but the end result is the same.
>>
>> Cheers,
>>
>> Bruce
>>
>>>
>>>> I don't have any big issues with the patch, but I just want to be sure,
>>>> since changing this default could change the configs of many defconfig
>>>> users, and they may have been unknowingly relying on the old behaviour.
>>>>
>>>
>>> I can understand that. But I don't see any other way to make the really
>>> expected behavior to work without risking breaking anything.
>>>
>>
>