[Letux-kernel] bloated defconfigs

Andreas Kemnade andreas at kemnade.info
Tue Jul 31 08:04:25 CEST 2018


On Sun, 29 Jul 2018 08:30:20 +0200
"H. Nikolaus Schaller" <hns at goldelico.com> wrote:

> Hi,
> 
> > Am 28.07.2018 um 15:04 schrieb Andreas Kemnade <andreas at kemnade.info>:
> > 
> > Hi,
> > 
> > I just stumbled upon our defconfigs.
> > 
> > andi at aktux:~/gta04/gta04-kernel$ ls -l arch/arm/configs/ -Sr | tail -n
> > 10 -rw-r--r-- 1 andi andi   9524 Apr  7 14:53 imote2_defconfig
> > -rw-r--r-- 1 andi andi   9985 Jul 28 13:34 imx_v6_v7_defconfig
> > -rw-r--r-- 1 andi andi  10118 Apr  7 14:53 ezx_defconfig
> > -rw-r--r-- 1 andi andi  10665 Apr  7 14:53 s3c2410_defconfig
> > -rw-r--r-- 1 andi andi  13161 May 29 18:14 omap2plus_defconfig
> > -rw-r--r-- 1 andi andi  17834 May 29 18:14 pxa_defconfig
> > -rw-r--r-- 1 andi andi  24624 Jul 28 13:34 multi_v7_defconfig
> > -rw-r--r-- 1 andi andi 157222 Jul 28 13:34 letux_udoo_defconfig
> > -rw-r--r-- 1 andi andi 157271 Jul 28 13:34 letux_lpae_defconfig
> > -rw-r--r-- 1 andi andi 157352 Jul 28 13:34 letux_defconfig
> > 
> > 
> > So we are bloated somehow.  
> 
> Yes, we git commit the full defconfig.
> 
> > So I am wondering how these defconfigs are
> > created. AFAIK the tool is
> > 
> > make ARCH=arm CROSS_COMPILE=... savedefconfig
> > 
> > the file can then be used as a defconfig. I just did it and copied it
> > over to .config and used
> > make ARCH=arm CROSS_COMPILE=... olddefconfig  
> 
> Indeed this tool can be used to shrink it to "differences".
> 
> > 
> > The result is the same. But the defconfig created by savedefconfig is
> > only 20KB. Well, what is the advantage? We have a better overview where
> > we have non-default values.  
> 
> Yes, but on the other hand we loose the overview what has been configured
> by looking just into the git tree. I often use this to check what is being
> done by Makefiles, especially with code I have never inspected before.
> So basically I am not really interested in the defaults...
> 
Well, there is a .config generated by make letux_defconfig somewhere in the checked
out tree. But when you want to maintain changes, it seems to be easier to have the
small variant. For example I have my flashing battery initramfs and want to
see messages while booting up, so I use a kernel with some more things compiled in
(which of course does not match letux philosophy). For new kernels I try
letux_defconfig first. It just feels more convenient to work on top of that reduced
defconfig. 
But lets more concentrate on fixing bugs.

Regards,
Andreas
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