[Gta04-owner] Little Debian Update

H. Nikolaus Schaller hns at goldelico.com
Mon Jan 29 12:31:39 CET 2018


> Am 29.01.2018 um 11:06 schrieb Josua Mayer <josua.mayer97 at gmail.com>:
> 
> Hi Nikolaus,
> 
> 
> Am 29.01.2018 um 10:55 schrieb H. Nikolaus Schaller:
>> Hi Josua,
>> 
>>> Am 29.01.2018 um 10:39 schrieb Josua Mayer <josua.mayer97 at gmail.com>:
>>> 
>>> My bugreport on adding the GTA04 to flash-kernel received a little
>>> attention:
>>> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=871792
>> Good!
>> 
>>> Vagrant Cascadian is asking for a list of u-boot variables that are set
>>> in our fork.
>> Hm. No idea... I'd say: just enough that it works :)
>> 
>>> Maybe one of you could jump in here?
>> You can add a printenv to our boot.scr right before the bootm is called.
>> (uncomment line 488 at http://git.goldelico.com/?p=gta04-uboot.git;a=blob;f=Letux/boot-scr/boot-gta04.txt#l488)
> Yes, I will do that in 2 to 3 weeks when lectures will have ended.
> Perhaps someone else can be quicker.
>> 
>>> 
>>> Am 26.01.2018 um 21:32 schrieb Josua Mayer:
>>>> Good day to you all,
>>>> 
>>>> I just want to notify everybody that Debian has finally enabled support
>>>> for compressed kernel modules in modprobe!
>>>> So maybe we can use compressed modules in the future.
>>>> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=772628
>>>> 
>>>> According to the changelog entry, they enabled xz.
>> That looks interesting.
>> 
>> I recently did something else: strip symbols from the kernel modules...
>> 
>> This reduced them from e.g. 128MB (compressed): http://download.goldelico.com/letux-kernel/letux-4.13/
>> down to 6.6MB (compressed): http://download.goldelico.com/letux-kernel/letux-4.14/
> What we are interested in is the size of the files on disk, not the size
> of the compressed deb.

Yes, indeed. But stripping reduces both significantly.

>> 
>> So I am not sure what additionally compressing the module binaries will
>> improve, considering that it is nowadays difficult to buy µSD cards smaller
>> than 4GB...
> NAND flash. I still think we will be able to put an OS in there.

Yes, it did work a while ago (maybe with Debian Wheezy).

Here it is

root at letux:~# du -s -h /lib/modules
32M     /lib/modules
root at letux:~# du -s -h /mnt/nand/lib/modules  
3.5M    /mnt/nand/lib/modules
root at letux:~#

When flashing, the NAND the flash-nand tool only copies those modules
that are really needed by the device.

I.e. the needed modules expanded are even smaller than the complete set
after compression.

So I think that optimizing just 1% of the total NAND footprint can be done,
but the bigger waste has to be removed before. And filtering seems to
be more efficient than compression.

> But yes, stripping is already reducing size very, very much.
> 
> In the bugreport for that feature I also argued that smaller files mean
> faster updates on slow (non-UHS-1) sdcards

BR,
Nikolaus



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