RT 4.19.71-rt24-v7l+ brakes USB on Raspberry PI 4 OS (Version 11/01/2021)

alkabal wrote: After apt-get upgrade usb boot killed.

Try again on the sdcard instal kernel and edit /boot/config-rt.txt but this file seem to be missing :
vmlinuz-5.4.83-rt48-v7l+

The kernel deb installs a new kernel7l instead.

tjtr33 wrote: Al
see
forum.linuxcnc.org/9-installing-linuxcnc...-2gb?start=20#195017
the usb fail on rpi-os is connected to memory
all rpi's fail at >=4meg

It isn't that simple. The 5.4-rt48 kernel works fine on my 4GB Pi400.

That kernel includes every patch from raspberry Pi up to last night, it should be the most up-to-date possible kernel, with all patches.

The links all lead to issues with the arm64 (64-bit) kernels. The -rt48 kernel is a 32-bit kernel.

Does the stock 32-bit kernel work with the Pi4-8GB?

I think that the only rational choice at this point it probably to abandon "official" Raspberry Pi support.

andypugh wrote:

alkabal wrote: After apt-get upgrade usb boot killed.

Try again on the sdcard instal kernel and edit /boot/config-rt.txt but this file seem to be missing :
vmlinuz-5.4.83-rt48-v7l+

The kernel deb installs a new kernel7l instead.

I have also try with this file (kernel7l) but i get "[brcmvirt_gpio_probe]: ]failed to dma_alloc_coherent(4096)"

Well, I am confused now.

Intending to investigate the effect of limiting memory to 3GB I made a new standard 32-bit SD card image, booted my new 2GB Pi4 (bought specifically to debug this reported issue) and followed the instructions here in the LinuxCNC docs:
linuxcnc.org/docs/2.8/html/getting-start...lling_on_raspbian_10
Contrary to the reports in this and other threads, it all "just worked".

I moved the SD card to my Pi400, and that worked, and then to my old 4GB Pi4, and that worked.

Is there _actually_ a problem?

And can we move all further discussion to this thread?
forum.linuxcnc.org/9-installing-linuxcnc...-work?start=0#194602