Document arm testing enviroment installation procedure

[aliceinwire]

Document arm testing enviroment installation procedure

[kuzetsa]

the current amd64 boot test is done using qcow image:

http://distfiles.gentoo.org/experimental/amd64/openstack/

I didn't see the analogous arm-type one available:

http://distfiles.gentoo.org/experimental/arm/openstack/

so perhaps a very minimalist boot tester like in this footnote:

#59 (comment)

intended / specific details for arm test need to be decided, I think

# using a cross toolchain for arm testing
  293  crossdev -S -t armv7a-hardfloat-linux-gnueabi
# confirmed nothing "weird" was recently modified:
  319  history | grep crossdev
# need kernel source to test the cross-toolchain:
  322  emerge '=sys-kernel/gentoo-sources-4.17.4'
# noticed it's not stable, so therefore did this:
  323  cd /etc/portage/package.keywords/
  326  nano -w crosscompile_kernel_arm 
  327  eshowkw gentoo-sources
# //still// need kernel source to actually test this:
  329  emerge '=sys-kernel/gentoo-sources-4.17.4'
# details for compiling a kernel omitted (for now)

[...]

# creating minimalist payload for qemu boot test:

{redacted / refer to updated documentation}

^ this type of initramfs can be used with qemu

a good qemu version (for arm) looks like this one:

#61 (comment)

example wrapper script for qemu-based test:

#!/bin/sh
# This script created by AQEMU
/usr/bin/qemu-system-arm -kernel $1 \
-initrd armpayload-initramfs.gz \
-machine virt -nographic -serial mon:stdio

A single argument is passed to this script:

just the name of the kernel, such as the compiled one
mentioned in the history entry 329 (see above)

the kernel version to be tested was compiled using this script:

#!/bin/sh
make \
ARCH=arm CROSS_COMPILE=armv7a-hardfloat-linux-gnueabi- \
--jobs 18 --load-average 19.9

note: there are a few ways to generate a .config
(board-specific defconfigs for arm are common)

[kuzetsa]

The specific init script I wrote is lazy / ugly [1], and was successfully
used for testing an arbitrary kernel [2] here's a (boot) log:

https://mouses.xyz/~kuzetsa/gentoo_tmp/arm_kernel_test.log

---

[1] - wiki.gentoo.org, on the topic of custom initramfs: "kernel panics"

[2] - crossarmkernel_build.log, cross-compiling a kernel for test (log)

[kuzetsa]

Tried to reproduce this environment today... dot dot dot

Discovered a gap in the documentation.
this is more correct (and more concise)

emerge-armv7a-hardfloat-linux-gnueabi busybox

[...]

last few lines of output contain:

Using system located in ROOT tree /usr/armv7a-hardfloat-linux-gnueabi/

>>> No outdated packages were found on your system.

and creating the busybox-based initramfs:

mkdir ./armpayload-qemu/
mkdir ./armpayload-qemu/bin/
cp -P /usr/armv7a-hardfloat-linux-gnueabi/bin/* ./armpayload-qemu/bin/
cd armpayload-qemu
nano -w ./init 
find . | cpio -R root:root -H newc -o | gzip > ../armpayload-initramfs.gz

github now offers the option to review past revisions of comments.
I'll editing the earlier / above comment for brevity.

[aliceinwire]

arm as been added in the testing enviroments