@Jeremy Last time I told you FOG’s server had no U-Boot support and your two
options were to keep hand-rolling it or put UEFI firmware on the Pi. That’s no
longer true - I built the server side. It’s merged into working-1.6 as of
1.6.0-beta.4318, so update and you’ll have it.
There’s a new endpoint:
http://<fogserver>/fog/service/uboot/boot.php?mac=<the Pi's MAC>
It answers with an extlinux.conf-style document, computed live from the
database. If the host has a task queued you get kernel/initrd/append for FOS;
if it doesn’t, you get localboot and U-Boot falls through to the disk. Fetch it
with curl first - the whole thing is plain text and readable, which is the
point.
On the Pi:
dhcp
setenv pxefile_addr_r 0x02000000
wget ${pxefile_addr_r} http://<fogserver>/fog/service/uboot/boot.php?mac=${ethaddr}
pxe boot ${pxefile_addr_r}
Use pxe boot, not sysboot. Every extlinux example you’ll find online shows
sysboot, and it’s wrong here - sysboot reads a config off a filesystem on a
block device, so it can’t see what wget just put in memory and does nothing
visible. That’s the one I’d expect to catch people out.
This should also fix your truncation. “Unknown request type :: Null” was $type
arriving empty because your bootargs were being cut short, and I pointed at
U-Boot’s command buffer rather than the kernel. pxe boot doesn’t go through
that buffer - it parses the append line out of the loaded file straight into
bootargs, so the ceiling you were hitting isn’t in the path any more. Worth
confirming, since I’m reasoning about your build rather than looking at it.
Two deliberate omissions, both because they’re properties of your board and not
of FOG:
FOG serves no device tree. No fdt or fdtdir directive, so you keep the tree at
${fdtcontroladdr} - the one VideoCore just built for the exact board revision
it’s running on, which is better than anything I could serve you. Load
addresses stay yours for the same reason.
And FOG writes no pxelinux.cfg files. The endpoint is stateless: the board asks
by MAC and gets an answer out of the database, so there’s nothing on disk to
drift from what’s actually queued and nothing to clean up when a task finishes.
One thing to check before you start: if your FOG install has netboot set to
HTTPS, none of this will work. U-Boot’s wget is HTTP-only with no TLS at all,
so it can’t even fail a certificate check - the redirect just ends the boot with
nothing on screen. The installer now exempts service/uboot/ from the HTTP-to-
HTTPS redirect the same way it does service/ipxe/, but only when netboot is
configured for HTTP in the first place.
Full write-up is in docs/UBOOT_ARM_BOOT.md in the repo.
Being straight about what this is: the emitted config is pinned byte-for-byte
by tests and the decisions behind it are the same code the iPXE path runs, so I
know FOG emits what I intended. What I can’t tell you is that a real U-Boot
consumes it, because nobody here has a Pi. You’re the only person who can prove
that, and if it’s wrong I’d rather hear it than not.
