The 9pi kernel source in /n/sources/contrib/miller/9/bcm on 9p.io has been updated with (very limited) support for the new pi4.
Reminder: 'srv -nq tcp!9p.io sources /n/sources' to get access to this mirror. Or point a browser at https://9p.io/sources/contrib/miller/9/bcm I'm not suggesting anyone should rush out to buy a pi4 just yet. Unlike previous releases of the board, this incarnation has some very big changes, so a lot of new driver writing will be needed before it's at all useful under Plan 9. It's quite daunting actually. Quoting 9/bcm/words.pi4: raspberry pi 4 -- work in progress! broadcom 2838 SoC (based on 2711 cpu) 4 x cortex-a72 (1500Mhz, out-of-order pipeline) Boots as far as the root prompt, but there are too many new peripherals without driver support (or documentation so far) to do anything useful. - usb host sockets are all connected to new usb3 controller - sdcard is connected to new emmc controller (can't use sdhost) - ethernet is connected to new native gbe controller Wifi is unchanged from 3B+, but currently fails intermittently with emmc IO_RW_EXTENDED data corruption. Needs firmware from 5 July 2019 or later. config.txt for pi4 should include 'core_freq=250' for the mini-uart console, and 'device_tree=' to ensure that the loader passes an ATAG list to the kernel instead of a device tree.
