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

[Christian Melki <christian.melki@t2data.com>]

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?

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

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