At the moment the U-Boot port for the DragonBoard 410c is designed
to be loaded as an Android boot image after Qualcomm's Little Kernel (LK)
bootloader. This is simple to set up but LK is redundant in this case,
since everything done by LK can be also done directly by U-Boot.
Dropping LK entirely has at least the following advantages:
- Easier installation/board code (no need for Android boot images)
- (Slightly) faster boot
- Boot directly in 64-bit without a round trip to 32-bit for LK
So far this was not possible yet because of unsolved problems:
1. Signing tool: The firmware expects a "signed" ELF image with extra
(Qualcomm-specific) ELF headers, usually used for secure boot.
The DragonBoard 410c does not have secure boot by default but the
extra ELF headers are still required.
2. PSCI bug: There seems to be a bug in the PSCI implementation
(part of the TrustZone/tz firmware) that causes all other CPU cores
to be started in 32-bit mode if LK is missing in the boot chain.
This causes Linux to hang early during boot.
There is a solution for both problems now:
1. qtestsign (https://github.com/msm8916-mainline/qtestsign)
can be used as a "signing" tool for U-Boot and other firmware.
2. A workaround for the "PSCI bug" is to execute the TZ syscall when
entering U-Boot. That way PSCI is made aware of the 64-bit switch
and starts all other CPU cores in 64-bit mode as well.
Simplify the dragonboard410c board by removing all the extra code that
is only used to build an Android boot image that can be loaded by LK.
This allows dropping the custom linker script, special image magic,
as well as most of the special build/installation instructions.
CONFIG_REMAKE_ELF is used to build a new ELF image that has both U-Boot
and the appended DTB combined. The resulting u-boot.elf can then be
passed to the "signing" tool (e.g. qtestsign).
The PSCI workaround is placed in the "boot0" hook that is enabled
with CONFIG_ENABLE_ARM_SOC_BOOT0_HOOK. The extra check for EL1 allows
compatibility with custom firmware that enters U-Boot in EL2 or EL3,
e.g. qhypstub (https://github.com/msm8916-mainline/qhypstub).
As a first step these changes apply only to DragonBoard410c.
Similar changes could likely also work for the DragonBoard 820c.
Note that removing LK wouldn't be possible that easily without a lot of
work already done three years ago by Ramon Fried. A lot of missing
initialization, pinctrl etc was already added back then even though
it was not strictly needed yet.
Cc: Ramon Fried <rfried.dev@gmail.com>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
This patch series adds support for ZFS listing and load to u-boot.
To Enable zfs ls and load commands, modify the board specific config file with
#define CONFIG_CMD_ZFS
Steps to test:
1. After applying the patch, zfs specific commands can be seen
in the boot loader prompt using
UBOOT #help
zfsload- load binary file from a ZFS file system
zfsls - list files in a directory (default /)
2. To list the files in zfs pool, device or partition, execute
zfsls <interface> <dev[:part]> [POOL/@/dir/file]
For example:
UBOOT #zfsls mmc 0:5 /rpool/@/usr/bin/
3. To read and load a file from an ZFS formatted partition to RAM, execute
zfsload <interface> <dev[:part]> [addr] [filename] [bytes]
For example:
UBOOT #zfsload mmc 2:2 0x30007fc0 /rpool/@/boot/uImage
References :
-- ZFS GRUB sources from Solaris GRUB-0.97
-- GRUB Bazaar repository
Jorgen Lundman <lundman at lundman.net> 2012.
0204d1b56b