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

[Alexandre Belloni <alexandre.belloni@free-electrons.com>]

Hi Bruce,

Any news on that ?

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=y
> >>>   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.
> >
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com