[U-Boot] [PATCH 0/3] imx: bootaux elf firmware support

[Lukasz Majewski]

Hi Stefan,

Thanks for your patch. Please allow me to share some ideas for
improvements.

> From: Stefan Agner <stefan.agner at toradex.com>
> 
> This patchset enables to boot elf binaries on secondary Cortex-M
> class cores available on i.MX 6SoloX/7Solo/7Dual. This makes
> handling and loading firmwares much more convinient since all
> information where the firmware has to be loaded to is contained in
> the elf headers. A typical usage looks like this:
> 
>   Colibri iMX7 # tftp ${loadaddr} firmware.elf && bootaux ${loadaddr}
>   Using FEC0 device
>   TFTP from server 192.168.10.1; our IP address is 192.168.10.2
>   Filename 'firmware.elf'.
>   Load address: 0x80800000
>   Loading: ##################################################  88.3
> KiB 5.4 MiB/s
>   done
>   Bytes transferred = 90424 (16138 hex)
>   ## Starting auxiliary core at 0x1FFF8311 ...
>   Colibri iMX7 #

I can find some other platforms (not only IMX), which would benefit
from this code - the generic 'bootaux' command.

One good example would to allow multiple binaries for different SoC
Cores (e.g. 2x Cortex-A8) to be loaded and started by u-boot.

Hence, I'm wondering if you could make those patches usable for other
platforms as well?

> 
> Note that the bootaux command retrieved the entry point (PC) from
> the elf binary.

Could you make this code flexible enough to handle not only elf
binaries, but also other data (e.g. FPGA bitstreams)?

Maybe it would better to:
-------------------------

Embrace those binaries into FIT file (*.itb)? And allow multiple
binaries loading? I'm thinking of work similar to one already did by
Andre Przywara for SPL:

"[PATCH v3 00/19] SPL: extend FIT loading support" posted on 31.03.2017?

In that way we would "open" many new use cases, and other platforms
(e.g. FPGA's, TI, etc) could benefit from it. 
One solid use case is to load different Linux binaries (or/and bare
metal programs) to different SoC cores.

The "meta data" (i.e. load address, data type, description), could be
extracted from the FIT format (the code is already in u-boot).

IMHO, this is very generic approach.

> Also all sections are translated to A7 addresses
> in order to properly load the firmware sections into the appropriate
> locations. 

This would require some tiny arch specific code.

> Also cache flushes is taken care of, so that there is no
> manual dcache flush necessary anymore.
> 
> The NXP FreeRTOS BSP already generates elf binaries which can be
> directly used with this elf binary support.
> 
> The last patch adds bootaux support for Vybrid.
> 
> 
> Stefan Agner (3):
>   imx: imx-common: move aux core image parsing to common code
>   imx: imx-common: add elf firmware support
>   ARM: vf610: add auxiliary core boot support
> 
>  arch/arm/cpu/armv7/mx6/soc.c                |  30 +++++---
>  arch/arm/cpu/armv7/mx7/soc.c                |  34 ++++++---
>  arch/arm/cpu/armv7/vf610/generic.c          |  42 +++++++++++
>  arch/arm/imx-common/Kconfig                 |   2 +-
>  arch/arm/imx-common/Makefile                |   4 +-
>  arch/arm/imx-common/imx_bootaux.c           | 105
> +++++++++++++++++++++++-----
> arch/arm/include/asm/arch-vf610/sys_proto.h |   8 +++
> arch/arm/include/asm/imx-common/sys_proto.h |   6 ++
> configs/colibri_vf_defconfig                |   1 + 9 files changed,
> 198 insertions(+), 34 deletions(-) create mode 100644
> arch/arm/include/asm/arch-vf610/sys_proto.h
> 




Best regards,

Lukasz Majewski

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