1So to make a Linux initrd: 2 3(1) mkdir .../initrd 4(2) mkdir -p .../initrd/boot/defaults 5(3) cd src/stand; make install DESTDIR=.../initrd 6(4) Copy kernel to .../initrd/boot/kernel 7(5) cd .../initrd 8(6) cp boot/loader.kboot init 9(7) find . | sort | cpio -o -H newc | gzip > /tmp/initrd.cpio 10(8) download or build your linux kernel 11(9) qemu-system-x86_64 -kernel ~/vmlinuz-5.19.0-051900-generic \ 12 -initrd /tmp/initrd.cpio \ 13 -m 256m -nographic \ 14 -monitor telnet::4444,server,nowait -serial stdio \ 15 -append "console=ttyS0" 16 (though you may need more than 256M of ram to actually boot FreeBSD and do 17 anything interesting with it and the serial console to stdio bit hasn't 18 been the most stable recipe lately). 19 20Notes: 21For #6 you might need to strip loader.kboot if you copy it directly and don't 22 use make install. 23For #7 the sort is important, and you may need LC_ALL=C for its invocation 24For #7 gzip is but one of many methods, but it's the simplest to do. 25For #9, this means we can automate it using methods from 26 src/tools/boot/rootgen.sh when the time comes. 27#9 also likely generalizes to other architectures 28For #8, see https://kernel.ubuntu.com/~kernel-ppa/mainline/ to download 29 a kernel suitable for testing... For arm, I've been using the 30 non 64k page kernels and 5.19 seems to not suck. 31 32aarch64: 33qemu-system-aarch64 -m 1024 -cpu cortex-a57 -M virt \ 34 -kernel ~/linuxboot/arm64/kernel/boot/vmlinuz-5.19.0-051900-generic \ 35 -initrd ~/linuxboot/arm64/initrd.img -m 256m -nographic \ 36 -monitor telnet::4444,server,nowait -serial stdio \ 37 -append "console=ttyAMA0" 38 39General 40 41Add -g -G to have gdb stop and wait for the debugger. This is useful for 42debugging the trampoline (hbreak will set a hardware break that's durable across 43code changes). If you set the breakpoint for the trampoline and it never hits, 44then there's likely no RAM there and you got the PA to load to wrong. When 45debugging the trampiline and up to that, use gdb /boot/loader. When debugging 46the kernel, use kernel.full to get all the debugging. hbreak panic() is useful 47on the latter since you'll see the original panic, not the panic you get from 48there not being an early console. 49