my phone is flame which is mozilla firefox os reference phone.

adb install
https://github.com/karfield/adb

sudo adb kill-server
sudo adb start-server

uncomment the [multilib] section in /etc/pacman.conf:

[multilib]
Include = /etc/pacman.d/mirrorlist

https://developer.mozilla.org/en-US/docs/Mozilla/Firefox_OS/Firefox_OS_build_prerequisites
Note that exclude mesa package due to systemd conflict.
i.e. run below command.

sudo pacman -S --needed alsa-lib autoconf2.13 bison ccache curl firefox flex gcc-multilib git gperf libnotify libxt libx11 multilib-devel wget wireless_tools yasm zip lib32-mesa lib32-mesa-libgl lib32-ncurses lib32-readline lib32-zlib lzop

kernel code fix

diff --git a/kernel/timeconst.pl b/kernel/timeconst.pl 
index eb51d76..0461239 100644 
--- a/kernel/timeconst.pl 
+++ b/kernel/timeconst.pl 
@ @ -370,7 +370,7 @ @ if ($hz eq '--can') { 
 	} 
  
 	@ val = @ {$canned_values{$hz}}; 
-	if (!defined(@ val)) { 
+	if (!@ val) { 
 	@ val = compute_values($hz); 
 	} 
 	output($hz, @ val);

runs firefox os (fox food version) fine on my flame :)