F21 System Wide Change: u-boot syslinux by default

[Peter Robinson]

>> Add syslinux support to u-boot enabling both pxelinux and extlinux support.
>> simplifying booting arm machines, making anaconda installs easy and overall
>> providing for a better user experience. Default u-boot to using syslinux config
>> files for booting. pxelinux for network and extlinux for local booting.
>
> At first I'm not familar with u-boot, but I wold to like any hard requirements
> for this feature:

This is targetted at ARM not x86 although things like chromebooks use
uboot too so it's not out of the question it could be used on x86.

> 1.) An bootloader for Fedora should support
>
>    * BIOS boot
>    * EFI boot  (used on Apple Mac computers)
>    * UEFI boot (with and without secure boot)

BIOS is irrelevant on ARM as it's a PC only technology, uEFI support
is coming to aarch64 and ARMv7 and we'll be supporting that as well
when it's ready and there's products shipping with it. We already have
aarch64 booting using standard uEFI.

> 2.) Dual-boot support. It should be possible to host serveral OSs on the same
> system. Aspecially the support of booting Windows may be very importent for
> the workstation product.

In the case of ARM Windows is irrelevant, Android yes and I've heard
of Android/Linux dual boot and this should be a usable option here but
it's untested.

> Additionally, whch filesystem are supported on u-boot? Can the /boot partition
> into a LVM. Grub2 support booting Linux from a /boot partition which is part
> of a LVM volumen group.

BIOS and uEFI doesn't support booting /boot from LVM and you need to
have grub on a supported file system the last time I looked. That said
we currently support extX and VFAT and I believe there's patches for
xfs and btrfs as well as some of the mobile FS too.

Ultimately this proposal is an extension and evolution of the process
we currently use to boot Fedora on ARM and is not affecting the
standard x86 process, Dennis should likely make this more clear in the
proposal.

Peter