[U-Boot] [PATCH 2/2] Enable PXE boot on meson-gxbb.

[Vagrant Cascadian <vagrant@debian.org>]

On 2017-04-17, Andreas Färber wrote:
> Am 18.04.2017 um 00:26 schrieb Vagrant Cascadian:
>> I guess I was referring to "source ${scriptaddr}; " line, which is quite
>> u-boot specific. I didn't realize that "DHCP" also had support for EFI
>> loaded over the network.
>
> DHCP just sets a filename that we can then load. What differs is where
> it gets loaded and what gets done with it next.

Sure, I see that.


>> It seems unforunate that the EFI network boot is only a fallback to
>> loading a boot script over the network, as boot scripts and EFI boot
>> seem to me like two unrelated features.
>> 
>> When loading from MMC, I think the order goes something like EFI,
>> extlinux, u-boot boot scripts.
>
> Nope, boot.scr goes before EFI also in the MMC case. That way I can have
> a boot.scr script on SD that applies overlays with fdt apply and then
> calls bootefi manually. And if anything goes wrong with the overlay, a
> simple exit from the GRUB prompt still boots me into a working system
> via the default EFI boot.

But not before the exlinux configuration in config_distro_bootcmd.h:

    "scan_dev_for_boot="                                              \
        "echo Scanning ${devtype} "                               \
                "${devnum}:${distro_bootpart}...; "       \
        "for prefix in ${boot_prefixes}; do "                     \
            "run scan_dev_for_extlinux; "                     \
            "run scan_dev_for_scripts; "                      \
        "done;"                                                   \
        SCAN_DEV_FOR_EFI                                          \

This loads the extlinux configuration before the boot scripts, and I'm
fairly sure that was intentional.

To me, the PXE boot is similar to the extlinux support; it loads the
same style configuration file, only one is over the network and one over
local media. To me, this looks like an inconsistancy in network boot
vs. local media boot with the order of which type of files are used to
boot.

Admittedly, the PXE boot method loads from so many fallback
locations it can be quite annoying.

Maybe I'm rehashing arguments already decided, and if so, perhaps these
should be documented in README.distro so there's a reference to point
to?


live well,
  vagrant
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