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Old 02-10-2014, 06:35 AM   #1
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Registered: Apr 2013
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Unhappy trying to open a virtual console on LCD using USB keyboard (embedded)

I'm trying to bring up virtual terminal on our embedded system's LCD usnig USB keyboard which is also connected to the system. I have UART connection to my PC so I've been using UART for console till now but I want to switch to framebuffer console on LCD during the boot at some point..

The USB host controller seems to work fine because I've seen USB memory is attached, read and written ok. And when I connect a keyboard and print the events at keyboard_event fuction, it prints events that seem normal and corresponding to my acion(type of key, press or release..)

I have a feeling that it's a configuration problem. In init/main.c, there is
(In my case, ramdisk_execute_command = "/sbin/init")

And this immediately calls
kernel_execve(init_filename, argv_init, envp_init);
// above, init_filename and argv_init are "/sbin/init" same.

I expect busybox to run after this.. (ramdisk had been installed before by a bootloader-like part) but I cannot see any prints on the LCD after this point. But I can see printks on the LCD until just before calling kernel_execve above. I'm using linux 3.3.

I understand I have to open a frame buffer console on LCD and connect it to a tty but I don't know how. Below are printed the current releavant settings. (In serial UART connection case, linux boots ok up to the final busybox shell prompt printing things in busybox initialization after kernel_execve call. and #cat /proc/fb0 returns 0 for your info. Only LCD/framebuffer console mode stops after kernel_execve.)

#### arch/sparc/boot/ourprocessor/prom_stage.c : #####
// "console=ttyS,mmio,0xff003000,115200n8 " <== serial port case
"console=tty " <= frame buffer console case (below line too)
"fbcon=font:SUN8x16,map:0000 " <= Is this boot argment correct?..

#### sbin/init: #####
#!/bin/busybox sh
export LD_LIBRARY_PATH=/lib
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/mnt/nand/lib

exec /bin/busybox init
### rcS #####
mknod /dev/tty0 c 4 0 <== Do I need to explicitly make tty0 and tty1 like this?
mknod /dev/tty1 c 4 1
mknod /dev/tty2 c 4 2
mknod /dev/tty3 c 4 3
mknod /dev/tty4 c 4 4

### .config #####
CONFIG_FRAMEBUFFER_CONSOLE=y <= LCD/framebuffer console case. Otherwise none.

By the way, I'm not using /etc/inittab.(so use default init). The busybox init/init.c code says if there isn't the inittab file and console is not the serial port, it runs
(starting shell on tty 2, 3 and 4) then How do make tty2's shell appear on the LCD/framebuffer/framebuffer console? It's confusing and books are not so kind..

Any hint would be deeply appreciated.

Thank you!


Last edited by flyxtop; 02-12-2014 at 05:28 AM. Reason: add some info


busybox, framebuffer, tty, virtual console

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