Mesa UART doesnt work after update to linuxcnc2.8

i was using linuxcnc 2.8 about 1 year ago,recently i decided to update it to release version 2.8.
Before updating, i can use multi UART channels but now only 1 channel work. example: i use 4 UART channels, only the channel 0 work, then i disable channel 0, channel 1 will work.
I tried look at uart.c in mesa-hostmot driver but nothing difference between them.

did you update the OS also to debian stretch
and the master is at 2.9

I did a quick look for an obvious commit - but found nothing obvious to me.
Can you use git bisect to find the commit that broke the behavior?

Also Andy P probably can make more intelligent suggestions -I'm sure he will chime in.

Chris M

Thats odd, I dont think there have been any UART related changes in 2.8 at all

The individual enable/disable logic seems to be in the mesa_uart component
so thats a likely suspect

1. i'm using linuxcnc 2.8 on Ubuntu 16.04 with Preempt-rt, i dont think it's a reason
2. i tried git bisect but i dont see any bad revision show up
3. Here is what happen after i make a deeper text:
+ I used 4 mesa_uart(modified), everything works well in my old version
+ When i use newer version 2.8.
- If i load 4 uart channels and use all, only channel 1 work but data store in channel 1 is come from channel 4.
- If i disable channel 1 (still load it) then channel 2 will work but data store in it also come from channel 4.
- if i disable channel 4( keep 1,2,3 running), not anychannel work, no data is stored

Is this on identical hardware/firmware as 2.7?