05-20-2015 02:07 AM
When I build a petalinux 2014.4 setup for a Zynq I see one tty in /dev/ and 64 ttyN devices. What are they (supposed to be) connected to? There is also ttyPS0 (and possibly ttyPS1) which is/are the ARM native uart. And if I add a uartlite to the PL I also get ttyUL0. So it's not these they're pointing to.
05-20-2015 02:58 AM
05-20-2015 03:46 AM - edited 05-20-2015 03:47 AM
The Linux kernel subsystem comprises of Character, Block, and Network drivers. The char and block drivers are present as device files in /dev. A char driver is one that can be accessed as a stream of bytes - /dev/ttyxx usually represent character drivers in the kernel.
The Zynq PS uart1 shows up as /dev/ttyPS0 in the kernel.
05-20-2015 04:13 AM
@balkris Thanks, interesting article but it says nothing about /dev/ttyxx only /dev/ttyPS0.
@sampatd I know that /dev/ttyxx represent character devices. My question is: what are these ones pointing to? I don't believe I have any other character devices that would qualify as a /dev/tty, but otherwise I would like to know which. Or are these some sort of mount points that newly plugged-in devices can take over? Not my experience. If I plug in a USB-UART it gets yet another /dev/ttyUSBx entry. So what's the use these 65 entries?
05-21-2015 07:50 AM
05-21-2015 09:09 AM
Ok, thanks. But what are they doing in my Zynq embedded linux? I have no keyboard with Ctrl, Alt or F2 keys. I also have no display. And even if I had, how would I press Ctrl-Alt-F63? Pressing Ctrl-Alt-F2 in a PuTTY SSH connection doesn't do anything. And neither does this in TeraTerm connected to the UART (ttyPS0). I still feel like most of them should disappear.