Clarify README section on differences with xz

[bearrito]

I'm not critiquing the decision, I'm trying to understand if there is a technical hurdle lurking in the background.

Right now we use xz as part of our A/B partition update for firmware like systems. As part of how the system works, we need to stream to stdout. The performance of pixz is impressive so we'd like to use it...

[vasi]

Stdout is totally supported! I can do cat SOMEFILE | pixz | wc -c and I get totally reasonable results. Is there some situation where stdout is not working for you?

[bearrito]

@vasi Maybe I'm misinterpreting this statement, my fault if so.

pixz does not support the command line option -c or --stdout

Namely we have something like this

xz -d -c $IMAGE_PATH | sudo dd skip=$SKIP_BLOCKS of=$PARTITION 

[vasi]

Ah, so your problem is we don't have the exact same arguments as xz. But you can still do the same operation, just worded a bit different:

pixz -d < $IMAGE_PATH | sudo dd skip=$SKIP_BLOCKS of=$PARTITION

Probably we should edit the README.md to be clearer!

[bearrito]

Thanks for the fast response. Get some sleep (or not) !
I'll try that tomorrow!

[vasi]

Updated the readme!