ccache and/or META_MODE for kernel dev

[jb82]

When working on a particular module within the kernel, WITH_META_MODE and/or WITH_CCACHE_BUILD are often used. Are there any easily identifiable caveats where it is not recommended to use either or both at the same time? My primary goal is to decrease compilation time.

 

[covacat]

building one module should be fast by default
when i hacked arm kernels i never used any of those and was building on a slow box
linking the kernel was the longest part

 

[william]

building one module should be fast by default
when i hacked arm kernels i never used any of those and was building on a slow box
linking the kernel was the longest part

Do you mind share with me your build machines and workflow? I am trying to do some FreeBSD kernel hacking and doing some "POC" on various vm platforms. The most annoying thing is long compilation/linking time.

Thanks.

 

[covacat]

for building just a vanilla module go to sys/module/the_module and make

for building a module with specific build options (that you should put in the KERNCONF file) see this post

Post in thread 'Can't detect wireless adapter BCM43225 despite if_bwn and bwn_v4_ucode loaded'

Oct 25, 2022

you need to build a kernel with options BWN_GPL_PHY
when i hacked the driver to try to use my BCM43228 i was building with this script

#!/bin/sh
COPTS=-g DEBUG=1 DEBUG_FLAGS=-g make KERN_OPTS="BWN_GPL_PHY BWN_DEBUG" && \
make install  && \
cp /boot/modules/if_bwn.ko /boot/kernel/ && \
cp if_bwn.ko.debug /usr/lib/debug//boot/kernel/if_bwn.ko.debug

use this patch along with the build see if it works
mine worked in the end but with crappy performance like under 1MB/s
if it panics when you using wpa_supplicant it might be a bad DMA buffer alignment
which i fixed but it was not enough...

• covacat

for building a kernel after some source changing
make KERNCONF=SOME_KERNEL -DNO_MODULES -DNOMODULES -DNOCLEAN -DNO_CLEAN buildkernel
then just copy the binary over with scp or what have you
you probably don't need both NO_SOMETHING and NOSOMETHING but i can't remember which one is the good one so i use both

now i build on a vm on a m4 mac mini which is very fast (linking kernel is not instant but ok) (i build arm kernels)
but i also used this CPU: AMD GX-217GA SOC with Radeon(tm) HD Graphics (1647.01-MHz K8-class CPU) for the bwn driver and anything in between