[syslinux] syslinux and btrfs-formatted dos/MBR partition

[David de Marneffe]

Hello syslinux list,

I have installed Arch over a btrfs-formatted dos/MBR primary
partition* (no btrfs subvolumes, just installing everything including
/boot in the root of the btrfs).

I have been unsuccessful for several days trying to get it to boot
with syslinux (6.02-8 package from Arch, also tried 4.07-1  Arch
package). All I am getting is the copyright header line and a blinking
cursor without keyboard control (can't type). No boot: prompt, no
menu, no response to CTRL-ALT-DEL (have to power off to reboot).

I am following the steps in Arch's beginner wiki and their syslinux
page (tried both the script provided by Arch and the manual method).
When I do this over ext4, everything works as expected, the copyright
line appears briefly then the menu pops up. No go with btrfs no matter
what I tried. So either it's a bug, or maybe I am repeatedly missing a
step?

It looks to me like the ldlinux.sys code embedded in the first 64k of
the btrfs partition crashes but no error message is generated. I have dd-ed
the first 64k of the btrfs partition and compared the file in a hex
editor with the ldlinux.sys file from an ext4 installation, and while
no exactly identical it seems to me that ldlinux.sys gets correctly
embedded as expected and does not overflow beyond the first 64k.

Any insight would be appreciated. I have been advised to talk to
Raphael_sc on irc about it, but I haven't managed to get a hold of him
so far.

* I am not using gpt because I want dual boot with winXP.