Linux 2.6-10.rc3 8xx - Only 3 characters are printed well in __ init start_kernel() upon kernel booting - why ?

Linux 2.6-10.rc3 8xx - Only 3 characters are printed well in __ init start_kernel() upon kernel booting - why ?

[Povolotsky, Alexander]

> Per kind advise I have got, I have added baud rate to the command =
line (I
> did not have it there before):
>=20
> CONFIG_CMDLINE=3D"console=3DttyCPM0,115200 panic=3D3 root=3D/dev/ram"
>=20
> 	However, my real current problem (just 3 characters get printed
> correctly during the kernel boot) did not go away.
>=20
> 	Is there a way to check if the baud rate specified in the .config's
> commandline is indeed in effect for the kernel booting ?
>=20
> 	Any other reasons/explanation for my "3 character" problem ?
>=20
> 	 -----Original Message-----
> 	From: 	Povolotsky, Alexander =20
> 	Sent:	Sunday, January 16, 2005 5:59 AM
> 	To:	'linuxppc-dev@ozlabs.org'
> 	Subject:	Linux 2.6-10.rc3  8xx kernel booting - how to set
> baud rate for the serial driver ?
>=20
> 	Hi,
> 	...=20
> 	    =20
> 	My bootloader uses 115200 baud rate for the serial output during
> boot strapping.
>=20
> 	I have:
> 	CONFIG_SERIAL_CPM_CONSOLE
> 	in my .config=20
> 	...=20
> I could see some output during the kernel boot -
> I noticed that (only 3) characters (see below) from the linux_banner =
are
> printed
> in __init start_kernel() upon booting . Then a lot of garbage is =
outputted
> and eventually kernel hangs ...
>=20
> after gunzip
> done.
> Now booting the kernel
> =
Lin=FF=FF=FF=FF=FF=FF=FF=FF=C0=FF=FF=FF=FF=FF=FF=FF=FF=C08=C0=FF=FF=FF=FF=
=FF=FF=FF=FF=C0X=C0=FF=FF=FF=FF=FF=FF=FF=FF=C0x=C0=FF=FF=FF=FF=FF=FF=FF=FF=
=C0~=C0=FF=FF=FF=FF=FF=FF=FF=FF=C0=B8=C0=FF=FF=FF=FF=FF=FF=FF
> =FF=C0=D8=C0=FF=FF
> <more garbage>
> <hangs>
>=20
> to prove it I added printk("ALEX\n"); in __init start_kernel() prior =
to
> printk(linux_banner);
>=20
> ...=20
> lock_kernel();
> page_address_init();
> printk("ALEX\n");
> printk(linux_banner);
> setup_arch(&command_line);
> setup_per_cpu_areas();
> ...
>=20
> after gunzip
> done.
> Now booting the kernel
> =
ALE=FF=FF=FF=FF=FF=FF=FF=FF=C0=FF=FF=FF=FF=FF=FF=FF=FF=C08=C0=FF=FF=FF=FF=
=FF=FF=FF=FF=C0X=C0=FF=FF=FF=FF=FF=FF=FF=FF=C0x=C0=FF=FF=FF=FF=FF=FF=FF=FF=
=C0~=C0=FF=FF=FF=FF=FF=FF=FF=FF=C0=B8=C0=FF=FF=FF=FF=FF=FF=FF
> =FF=C0=D8=C0=FF=FF
> <more garbage>
> <hangs>
>=20
> Why would first 3 characters come out right ?
> Any ideas ?
> Thanks,
>=20

Re: Linux 2.6-10.rc3 8xx - Only 3 characters are printed well in __ init start_kernel() upon kernel booting - why ?

[David Jander]

On Sunday 16 January 2005 20:54, Povolotsky, Alexander wrote:
>[...]
> > to prove it I added printk("ALEX\n"); in __init start_kernel() prior to
> > printk(linux_banner);
> >
> > ...
> > lock_kernel();
> > page_address_init();
> > printk("ALEX\n");
> > printk(linux_banner);
> > setup_arch(&command_line);
> > setup_per_cpu_areas();
> > ...
> >
> > after gunzip
> > done.
> > Now booting the kernel
> > ALE=FF=FF=FF=FF=FF=FF=FF=FF=C0=FF=FF=FF=FF=FF=FF=FF=FF=C08=C0=FF=FF=FF=
=FF=FF=FF=FF=FF=C0X=C0=FF=FF=FF=FF=FF=FF=FF=FF=C0x=C0=FF=FF=FF=FF=FF=FF=FF=
=FF=C0~=C0=FF=FF=FF=FF=FF=FF=FF=FF=C0=B8=C0=FF=FF=FF=FF=FF=FF
> >=FF =FF=C0=D8=C0=FF=FF
> > <more garbage>
> > <hangs>
> >
> > Why would first 3 characters come out right ?
> > Any ideas ?

My fairly uneducated guess: The system hangs before the last character come=
s=20
out of the uart buffer. Try adding a delay just after printk.
The garbage could be anything produced by a piece of hardware gone wild.

Greetings,

=2D-=20
David Jander
Protonic Holland.