Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[Antonio Diaz Diaz]

Mioljub Ivanovic wrote:

Do I need (since I have lzipped kernel) lzipped* kexec-tools?


It seems from the code that the answer is yes.

I have managed to write a patch for kexec-tools-2.0.17. It compiles 
cleanly on my machine, but I can't test it. The kernel in my machine is 
not configured for kexec-tools.


Please, test the patch and report any problems you find.


Best regards,
Antonio.


kexec-tools-2.0.17_lzip-0.diff.lz
Description: Unix tar archive
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Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[wrotycz]

If the changes required are easy, they may be ready in a few days. Else  it may 
take longer.   BTW, has anybody verified if this change is worth the effort? 
I.e., has  LZMA compression any advantages over gzip compression for kernel 
modules?   I can test it if its not too complicated. I mean I know how to 
compile kernel and run new one but dont know whats kmod is all about 
so youll need to give some source where I can read about it bit more.   
When it comes to modules I made small test and result should be self 
explaining:  ~/tmp/modules $ for DIR in `ls -1`; do du -sk $DIR; done

# unstripped
242644  236.95[MiB]  stripped
123776  120.87[MiB] mo  So the difference for unstripped modules is 20% 
less (than gzip) for lzma but for unstripped modules its 8%.   Is it only 
8% or antonym to only 8% is question of interpretation in this case but 
generally compressing unused modules is definitely good thing. In my case 
modules in memory take 14MiB, so saving 180/80[MiB] is definitely a good thing 
even today when computers have tons of RAM.
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Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[Antonio Diaz Diaz]

Daniel Baumann wrote:

not sure if this is representative, but naively compression all *.ko of
the /lib/modules directory of the current debian default kernel with
lzip looks like this:

daniel@daniel:~/4.15.0-2-amd64$ du -sh
248M.
daniel@daniel:~/4.15.0-2-amd64$ cd ../4.15.0-2-amd64.lzip
daniel@daniel:~/4.15.0-2-amd64.lzip$ du -sh
60M .


Interesting. Thanks.


Best regards,
Antonio.

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Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[Antonio Diaz Diaz]

Matias Fonzo wrote:

Is this the source I need to patch?
http://mirrors.edge.kernel.org/pub/linux/utils/kernel/kmod/kmod-25.tar.gz


Yes, that is the latest version.


Thanks. I'll look into it ASAP.

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Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[Daniel Baumann]

On 04/16/2018 11:56 PM, Antonio Diaz Diaz wrote:
> I.e., has LZMA compression any advantages over gzip compression for kernel 
> modules?

not sure if this is representative, but naively compression all *.ko of
the /lib/modules directory of the current debian default kernel with
lzip looks like this:

daniel@daniel:~/4.15.0-2-amd64$ du -sh
248M.
daniel@daniel:~/4.15.0-2-amd64$ cd ../4.15.0-2-amd64.lzip
daniel@daniel:~/4.15.0-2-amd64.lzip$ du -sh
60M .
daniel@daniel:~/4.15.0-2-amd64.lzip$

Regards,
Daniel

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Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[Matias Fonzo]

On Mon, 16 Apr 2018 23:56:18 +0200
Antonio Diaz Diaz  wrote:

> Mioljub Ivanović wrote:
> > Please would You send me script for recursively uncompressing
> > lzipped kernel modules in kernel modules folder.  
> 
> My machine does not have a /proc/modules directory, so I'm not sure
> if the following command will work for you:
> 
> 'lzip -d /*.lz'
> 

He can try adding it to the mkinitcpio command?.

> 
> > I will wait for Your unofficial patch for kmod - I have also one
> > question about kmod experimental features, I just compiled kmod git
> > version without experimental features.  
> 
> I'm afraid I can't answer any questions about kmod. I know very
> little about it.
> 
> Is this the source I need to patch?
> http://mirrors.edge.kernel.org/pub/linux/utils/kernel/kmod/kmod-25.tar.gz

Yes, that is the latest version.
 
> If the changes required are easy, they may be ready in a few days.
> Else it may take longer.

If the code is prepared for several formats, it should be easy, I guess.
 
> BTW, has anybody verified if this change is worth the effort? I.e.,
> has LZMA compression any advantages over gzip compression for kernel
> modules?
> 

Probably, only in terms of size.


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Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[Antonio Diaz Diaz]

Mioljub Ivanović wrote:

Please would You send me script for recursively uncompressing lzipped kernel
modules in kernel modules folder.


My machine does not have a /proc/modules directory, so I'm not sure if 
the following command will work for you:


'lzip -d /*.lz'



I will wait for Your unofficial patch for kmod - I have also one question about
kmod experimental features, I just compiled kmod git version without
experimental features.


I'm afraid I can't answer any questions about kmod. I know very little 
about it.


Is this the source I need to patch?
http://mirrors.edge.kernel.org/pub/linux/utils/kernel/kmod/kmod-25.tar.gz

If the changes required are easy, they may be ready in a few days. Else 
it may take longer.


BTW, has anybody verified if this change is worth the effort? I.e., has 
LZMA compression any advantages over gzip compression for kernel modules?



Best regards,
Antonio.

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Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[Antonio Diaz Diaz]

Thanks Matias.

Matias Fonzo wrote:

Yes.  It is true that you can patch the kernel against aufs, and also
there is an available patch from the Lzip project to add support of
lzip into the kernel, this support is currently limited for compressed
initramfs.  Lzip won't work for the kernel modules, cause the support
is needed in the kmod side.  There is one thing to do, request the
support of lzip in kmod.. which will be hard because they match the
available formats in the kernel, lzip was proposed to the linux kernel
developers some time ago, without an answer yet...

Always exist the possibility to make an unofficial patch.  :-)


I certainly can make an unofficial patch for kmod, as long as somebody 
else volunteers to test it and perhaps propose it upstream.



Best regards,
Antonio.

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Re: [Lzip-bug] I have some practical question about lzip patch for linux kernel (about lzip-ed kernel modules)

[Matias Fonzo]

Hello,

On Mon, 16 Apr 2018 16:06:11 +0200
"Mioljub Ivanović"  wrote:

> I just compiled linux-4.14.33 kernel patched with aufs and lzip patch
> with following .config file - I used lzip compression also to
> compress kernel modules. You can see this in my .config file. I
> compiled kmod with experimental features and I got the following
> result using ArchLinux mkinitcpio command. In file
> mkinitcpio-with-lz-log.txt You can see that kmod does not work with
> lzip-ed kernel modules only gzip-ed and xz-ed. Please, would You send
> me lzip patch for kmod.

Yes.  It is true that you can patch the kernel against aufs, and also
there is an available patch from the Lzip project to add support of
lzip into the kernel, this support is currently limited for compressed
initramfs.  Lzip won't work for the kernel modules, cause the support
is needed in the kmod side.  There is one thing to do, request the
support of lzip in kmod.. which will be hard because they match the
available formats in the kernel, lzip was proposed to the linux kernel
developers some time ago, without an answer yet...

Always exist the possibility to make an unofficial patch.  :-)



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