chore(zone): clean up and reduce linux config

[alexandermerritt]

Our current fragment is quite small.

What that means: default-enabled config options in Kconfig that are not explicitly disabled in our fragment, will be enabled once merged with a defconfig for the architecture. Examples include wireless hardware support and networking, bluetooth, sound, etc. which we all do not need for zone kernels.

Goals: reduce the amount of text in the kernel, second to reduce build times.

Add many is not set for any default-enabled configuration options we do not want. For future kernels, we'll need to check for any newly introduce configuration options that are default-enabled and repeat for them.

[alexandermerritt]

Un-drafting for the moment while I test e2e on this, to get some eyes on the changes.

[alexandermerritt]

I'd like to merge each commit separately... I may have to do that via individual PRs.

[bleggett]

Goals: reduce the amount of text in the kernel, second to reduce build times.

Curious (i.e. not an ask): did you do a before/after to see if/by how much this shrinks the (uncompressed) kernel/module image?

[alexandermerritt]

Goals: reduce the amount of text in the kernel, second to reduce build times.

Curious (i.e. not an ask): did you do a before/after to see if/by how much this shrinks the (uncompressed) kernel/module image?

~> ll bzImage*
-rw-rw-r-- 1 alexm alexm 26M Aug 18 20:45 bzImage.main
-rw-rw-r-- 1 alexm alexm 18M Aug 18 20:18 bzImage.slim

~> src/linux-6.18.44-x86_64/scripts/extract-vmlinux bzImage.main >vmlinux.main
extract-vmlinux: Extracted vmlinux using 'unzstd' from offset 21197

~> src/linux-6.18.44-x86_64/scripts/extract-vmlinux bzImage.slim >vmlinux.slim
extract-vmlinux: Extracted vmlinux using 'unzstd' from offset 21197

~> ll vmlinux*
-rw-rw-r-- 1 alexm alexm 104M Aug 18 20:48 vmlinux.main
-rw-rw-r-- 1 alexm alexm  76M Aug 18 20:48 vmlinux.slim

~> readelf -S vmlinux.main --wide | head
There are 45 section headers, starting at offset 0x6400228:

Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            0000000000000000 000000 000000 00      0   0  0
  [ 1] .text             PROGBITS        ffffffff81000000 200000 2577368 00  AX  0   0 4096
[ 2] .rodata           PROGBITS        ffffffff83600000 2800000 db5536 00  WA  0   0 4096

# 37M .text and 14M .rodata

~> readelf -S vmlinux.slim --wide | head
There are 45 section headers, starting at offset 0x4a00228:

Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            0000000000000000 000000 000000 00      0   0  0
  [ 1] .text             PROGBITS        ffffffff81000000 200000 184cf60 00  AX  0   0 4096
  [ 2] .rodata           PROGBITS        ffffffff82a00000 1c00000 90ff36 00  WA  0   0 4096

# 24M .text and 9M .rodata

The fetched kernel from protect's hack/kernel/fetch.sh produces a bzImage 14M in size (compared to the build above on main giving me 26M).

These are based on my builds locally, there is a 30% reduction in size, and ~13m build time on 32 cores to ~8m.

[alexandermerritt]

Closes https://github.com/edera-dev/protect/issues/3196