SMlight SMHUB OpenWrt support

For Developers
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I have just booted a linux (very near) mainline 6.18-rc1 from https://github.com/sophgo/linux-riscv with just very small DTS-patches to serial console login into the SMHub-OS rootfs.

Will now make a DTS-file for the SMHUB specifically, so that ethernet and wifi can be used, and compile a new image with USB gadget and wifi drivers.

1 Like
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So first steps are done.

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I can now boot (with my 6.18-rc1) the smhub into a Debian Trixie RiscV-installation (installed into /mnt/user from OEM FW), and have working Ethernet, eMMC, and SD-Card, and all serial ports. Not working for now is Wifi/BT (aic8800-sdio) and USB (OTG driver is detected, but ā€¦ is donā€™t get a UDC, or role_switch endpoint). So I could now start using it as remote radios for my homeassistant via ser2net/socat. Iā€™ll write some glue scripts to announce the RGB lights and other sensors via mosquitto_pub.

Iā€™m assuming, that 6.18 will be called as LTS, and that at some point after the 6.12 era, OpenWrt will start porting RiscV to 6.18 (or later). At that point Iā€™ll attempt to get this device supported under OpenWrt.

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Does this change effect booting custom images or other OSes?

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I donā€™t think so. If youā€™ve already installed it, check if you can sudo -i to root, and whether they have updated the kernel.

Meanwhile, Iā€™ve hit a roadblock:
https://lists.debian.org/deity/2024/05/msg00021.html (Near the bottom):

0x8330000f is FENCE.TSO, which some of the T-Head cores notoriously
failed to implement, thereby violating the RISC-V spec. LLVM has
emitted it for a long time, but GCC didnā€™t until recently (14.1) so
without doing proper architectural testing, just running Linux on top
of it historically wouldnā€™t have revealed the issue.

OpenSBI 1.1 (released June 2022) emulates the instruction for this
hardware, so update your firmware to a version that includes a
recent-ish version of OpenSBI and pretends your hardware is more
conforming.

The SMHub device ships with OpenSBI 0.9, which is 5 years old. Upstream OpenSBI is at 1.9, and supports Sophgo CV18xx/SG2000 since version 1.5 from June 2024. The OpenSBI is contained (afaict) in the FIP.bin, which (afaiu) are stored in the mmcblk0boot0 and ā€¦1.

Iā€™ll now be checking the upstream sources (milkv/sophgo) to see, whether any of those have/use a newer OpenSBI/FIP/U-Boot in their boad support images. It looks like I might be able to use SD-Card boot to ā€œtest outā€ other FIPs. (If the default stage1 bootloader defaults to reading SD first, then eMMC, which I think it does, but canā€™t find in writing just now).
If I find a build recipe for the fip.bin, and how to test safely, I plan to build a full-featured U-boot (with EFI-features etc.) with a mainline up2date OpenSBI 1.9+.

1 Like
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If you put the fip.bin on a FAT sd-card, the bootloader ROM loads it and flashes it to the 2 hardware boot partitions.