
How the ARM32 Linux kernel decompresses - zdw
https://people.kernel.org/linusw/how-the-arm32-linux-kernel-decompresses
======
jandrese
I have to wonder just how relevant all of this effort is anymore. They're
talking about faster reads and saving space, but the savings is _seven
megabytes_. And even then it comes at the cost of leaving dead space
underneath your kernel space in main memory where the old compressed kernel
used to be.

They're doing all of this on systems frequently running off of 16 or 32GB
flash devices. The difference in cost between manufacturing a 16MB flash
device and a 512MB flash device these days must be minuscule.

~~~
leeter
It's cents... but consider this. Linux is run on devices embedded in just
about everything. Places where even doubling from 128 to 256MB of flash ROM
could seriously hurt margins. So as the old saying goes.. a penny here and
penny there sooner or later you're talking real money. And it is real money
sometimes millions of dollars in margin.

~~~
andyjpb
Cents is a lot of money in manufacturing.

When I made consumer electronics our production team would swap parts based on
cost. 1c on a million units is $10,000. They only had to save a few cents a
year each to easily pay for themselves.

The rest was margin for the business.

Saving cents on a $80 BOM (bill of materials) may not sound like much but it
really does add up when you're doing volume manufacturing.

~~~
andyjpb
On the other hand, manufacturing has the general attitude that "software is
free" because the incremental cost in production to make a copy is zero.

Once, the production team swapped a component as part of a running change and
it took a programmer nearly a month to write the new driver.

I think we still came out ahead in the end but there was some worry along the
way as it wasn't clear how long it was going to take.

------
ncmncm
It is so sad to see gzip still used these days. If boot time matters, how much
faster would it be with lz4 or even zstd? Or are those actually used now, on
ARM bootloaders?

------
voltagex_
This is pretty "new" in terms of some of the devices I've seen. I wonder what
it looked like before DTBs were a thing.

~~~
ComputerGuru
It touches on that with the ATAG instead of DTB.

