Re: [ptxdist] [PATCH] image-root-cpio: Add compressor options to the env.

[Michael Olbrich <m.olbrich@pengutronix.de>]

On Fri, Mar 04, 2022 at 10:21:24AM +0100, Christian Melki wrote:
> 
> 
> On 3/4/22 10:09 AM, Michael Olbrich wrote:
> > On Thu, Mar 03, 2022 at 11:25:05PM +0100, Christian Melki wrote:
> > > * xz needs crc32 instead of crc64 for the kernel cpio.
> > 
> > Good point. I didn't know about that.
> > 
> > > * Set zstd compression level to the same as for the kernel (19).
> > 
> > Makes sense.
> > 
> > > * Use multithreading for zstd (deterministic, afaiu).
> > 
> > It is. I looked into this because I was curious. And it makes sense. zstd
> > was developed at a time when reproducibility was already important.
> > 
> > > Actively decided against -T0 for xz, as compression
> > > is not deterministic when number of threads varies.
> > 
> > We definitively want to be reproducible here.
> > 
> > > Signed-off-by: Christian Melki <christian.melki@t2data.com>
> > > ---
> > >   rules/image-root-cpio.make | 3 +++
> > >   1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/rules/image-root-cpio.make b/rules/image-root-cpio.make
> > > index fdb0ccfff..eb09dd53e 100644
> > > --- a/rules/image-root-cpio.make
> > > +++ b/rules/image-root-cpio.make
> > > @@ -26,6 +26,9 @@ IMAGE_ROOT_CPIO_CONFIG	:= cpio.config
> > >   IMAGE_ROOT_CPIO_ENV := \
> > >   	FORMAT="newc" \
> > > +	ZSTD_CLEVEL="19" \
> > > +	ZSTD_NBTHREADS="0" \
> > > +	XZ_OPT="--check=crc32" \
> > >   	COMPRESS=$(call remove_quotes, $(PTXCONF_IMAGE_ROOT_CPIO_COMPRESSION_UTIL))
> > 
> > Add the options to the PTXCONF_IMAGE_ROOT_CPIO_COMPRESSION_UTIL defaults
> > and keep the quotes here:
> > 
> > 	COMPRESS=$(PTXCONF_IMAGE_ROOT_CPIO_COMPRESSION_UTIL)
> > 
> > genimage explicitly does not quote to make to possible to specify the
> > compressor with options. At least I thinks that should work.
> > 
> > And maybe we could add a IMAGE_ROOT_CPIO_COMPRESSION_MODE_CUSTOM and then
> > add 'prompt "suffix" if IMAGE_ROOT_CPIO_COMPRESSION_MODE_CUSTOM' to the
> > suffix and similar for the util.
> > 
> > This way the user could tweak things if absolutely necessary.
> > 
> > What do you think?
> 
> I don't mind, will fix. But custom compressors will be outside of the
> ptxdist dependency scope for building host binaries?
> I can make a note about it in the help?

Right, I forgot about that. That's not good. So maybe:

config IMAGE_ROOT_CPIO_CUSTOM_COMPRESSION
	bool
	prompt "customise the compression command"

outside the choice and only add the optional prompt to the util. So we
still choose a type with its dependency.

We could also split the options into a separat symbol and only add the
prompt there, but I'm not so sure if that makes it better.

Michael

> > 
> > Michael
> > 
> > >   ifdef PTXCONF_IMAGE_ROOT_CPIO
> > > -- 
> > > 2.30.2
> > > 
> > > 
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> > > 
> > 
> 
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