Disable EARLY_PRINTK on IP22 to make the system boot

Disable EARLY_PRINTK on IP22 to make the system boot

[Martin Michlmayr]

Some Debian users have reported that the kernel hangs early
during boot on some IP22 systems.  Thomas Bogendoerfer found
that this is due to a "bad interaction between CONFIG_EARLY_PRINTK
and overwritten prom memory during early boot".  Since there's
no fix yet, disable CONFIG_EARLY_PRINTK for now.

Signed-off-by: Martin Michlmayr <tbm@cyrius.com>

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 1aad0d9..42e1ac1 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -358,7 +358,9 @@ config SGI_IP22
 	select SWAP_IO_SPACE
 	select SYS_HAS_CPU_R4X00
 	select SYS_HAS_CPU_R5000
-	select SYS_HAS_EARLY_PRINTK
+# Disable EARLY_PRINTK for now since it leads to overwritten prom memory
+# during early boot on some machines.
+#	select SYS_HAS_EARLY_PRINTK
 	select SYS_SUPPORTS_32BIT_KERNEL
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_BIG_ENDIAN

-- 
Martin Michlmayr
http://www.cyrius.com/

Re: Disable EARLY_PRINTK on IP22 to make the system boot

[Dmitri Vorobiev]

On Thu, Nov 19, 2009 at 6:40 PM, Martin Michlmayr <tbm@cyrius.com> wrote:
> Some Debian users have reported that the kernel hangs early
> during boot on some IP22 systems.  Thomas Bogendoerfer found
> that this is due to a "bad interaction between CONFIG_EARLY_PRINTK
> and overwritten prom memory during early boot".  Since there's
> no fix yet, disable CONFIG_EARLY_PRINTK for now.

Never experienced anything like that, although I'm quite extensively
using IP22 with recent kernels. Any details on the hangs?

Thanks,
Dmitri

>
> Signed-off-by: Martin Michlmayr <tbm@cyrius.com>
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 1aad0d9..42e1ac1 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -358,7 +358,9 @@ config SGI_IP22
>        select SWAP_IO_SPACE
>        select SYS_HAS_CPU_R4X00
>        select SYS_HAS_CPU_R5000
> -       select SYS_HAS_EARLY_PRINTK
> +# Disable EARLY_PRINTK for now since it leads to overwritten prom memory
> +# during early boot on some machines.
> +#      select SYS_HAS_EARLY_PRINTK
>        select SYS_SUPPORTS_32BIT_KERNEL
>        select SYS_SUPPORTS_64BIT_KERNEL
>        select SYS_SUPPORTS_BIG_ENDIAN
>
> --
> Martin Michlmayr
> http://www.cyrius.com/
>
>

Re: Disable EARLY_PRINTK on IP22 to make the system boot

[Martin Michlmayr]

* Dmitri Vorobiev <dmitri.vorobiev@gmail.com> [2009-11-19 18:56]:
> > Some Debian users have reported that the kernel hangs early
> > during boot on some IP22 systems.  Thomas Bogendoerfer found
> > that this is due to a "bad interaction between CONFIG_EARLY_PRINTK
> > and overwritten prom memory during early boot".  Since there's
> > no fix yet, disable CONFIG_EARLY_PRINTK for now.
> 
> Never experienced anything like that, although I'm quite extensively
> using IP22 with recent kernels. Any details on the hangs?

It doesn't happen on all machines.  It has been reported e.g. with an
Indigo2.  See http://bugs.debian.org/507557

Since Thomas Bogendoerfer disagnosed the problem, he should be able to
say more.

-- 
Martin Michlmayr
http://www.cyrius.com/

Re: Disable EARLY_PRINTK on IP22 to make the system boot

[Dmitri Vorobiev]

On Thu, Nov 19, 2009 at 7:00 PM, Martin Michlmayr <tbm@cyrius.com> wrote:
> * Dmitri Vorobiev <dmitri.vorobiev@gmail.com> [2009-11-19 18:56]:
>> > Some Debian users have reported that the kernel hangs early
>> > during boot on some IP22 systems.  Thomas Bogendoerfer found
>> > that this is due to a "bad interaction between CONFIG_EARLY_PRINTK
>> > and overwritten prom memory during early boot".  Since there's
>> > no fix yet, disable CONFIG_EARLY_PRINTK for now.
>>
>> Never experienced anything like that, although I'm quite extensively
>> using IP22 with recent kernels. Any details on the hangs?
>
> It doesn't happen on all machines.  It has been reported e.g. with an
> Indigo2.  See http://bugs.debian.org/507557

Interesting, thanks. Good to know that, since one of my machines is Indigo2.

>
> Since Thomas Bogendoerfer disagnosed the problem, he should be able to
> say more.

OK.

Dmitri

>
> --
> Martin Michlmayr
> http://www.cyrius.com/
>

Re: Disable EARLY_PRINTK on IP22 to make the system boot

[Thomas Bogendoerfer]

On Thu, Nov 19, 2009 at 10:05:06PM +0200, Dmitri Vorobiev wrote:
> On Thu, Nov 19, 2009 at 7:00 PM, Martin Michlmayr <tbm@cyrius.com> wrote:
> > * Dmitri Vorobiev <dmitri.vorobiev@gmail.com> [2009-11-19 18:56]:
> >> > Some Debian users have reported that the kernel hangs early
> >> > during boot on some IP22 systems.  Thomas Bogendoerfer found
> >> > that this is due to a "bad interaction between CONFIG_EARLY_PRINTK
> >> > and overwritten prom memory during early boot".  Since there's
> >> > no fix yet, disable CONFIG_EARLY_PRINTK for now.
> >>
> >> Never experienced anything like that, although I'm quite extensively
> >> using IP22 with recent kernels. Any details on the hangs?
> >
> > It doesn't happen on all machines.  It has been reported e.g. with an
> > Indigo2.  See http://bugs.debian.org/507557
> 
> Interesting, thanks. Good to know that, since one of my machines is Indigo2.

I guess is depending on RPOM version and installed memory. I haven't
figured out exactly which parts get overwritten, but since we completely
ignore ARCS reservered memory and still use ARCS prom calls, it's not
a real safe game we are doing.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessary a
good idea.                                                [ RFC1925, 2.3 ]

Re: Disable EARLY_PRINTK on IP22 to make the system boot

[Ralf Baechle]

On Thu, Nov 19, 2009 at 04:40:09PM +0000, Martin Michlmayr wrote:

> Some Debian users have reported that the kernel hangs early
> during boot on some IP22 systems.  Thomas Bogendoerfer found
> that this is due to a "bad interaction between CONFIG_EARLY_PRINTK
> and overwritten prom memory during early boot".  Since there's
> no fix yet, disable CONFIG_EARLY_PRINTK for now.
> 
> Signed-off-by: Martin Michlmayr <tbm@cyrius.com>

Patch looks ok but I think IP28 needs the same change applied.  Will post
a new patch in separate mail.

  Ralf