From: Jaap van den Handel <jaap@qu...> - 2004-07-29 15:57:31
The framebuffer driver for our vga device is working.
But when we tried to boot with the console directing to it, it crashed.
We are running linux 2.4.20 on an embedded MIPS @ 175MHz with a terminal=20
attached to a serial port. When we specify "console=3Dtty0" the console i=
switched from the serial console to the framebuffer console when our=20
framebuffer driver is loaded.
we found that while switching the console, it is not disabled. The consol=
switched and before it is fully initialzed, something is already printing=
when we disabled the console during a switch by setting=20
"printable =3D 0;" at the beginning of "take_over_console.c" in drivers/c=
at the end of "take_over_console" we set it back to 1.
after this we were able to boot and see the pinguin logo with a cursor.
since it is not possible to attach a keyboard we tried=20
"echo some text > /dev/tty0" and "some text" does appear at the framebuff=
Did we miss a setting to disable writes to the console while initializing=
Is it a bug which only comes forward in combination with a serial console=
relative slow cpu's?
Jaap van den Handel
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From: Carlos Manuel Duclos Vergara <carlos@em...> - 2004-07-29 16:05:12
the console is enabled very early in the boot process in order to print some
info about the boot process itself. Read start_kernel() in
for more info
Carlos Manuel Duclos Vergara
From: Antonino A. Daplas <adaplas@ho...> - 2004-07-29 20:53:11
On Thursday 29 July 2004 23:57, Jaap van den Handel wrote:
> Did we miss a setting to disable writes to the console while initializing
> our driver?
> Is it a bug which only comes forward in combination with a serial console
> or relative slow cpu's?
This is a problem in 2.4, hopefully fixed by BenH in 2.6 by acquiring the
console semaphore at strategic places.
Try placing acquire_console_sem(), release_console_sem() around the loop
in take_over_console() to disable early printing during console initialization.