Re: Kernel Preemption patch

Re: Kernel Preemption patch

[Wolfgang Denk]

In message <995FF289C9D69747A09E42992644595405B23683@penguin.adic.com> you wrote:
>
> - I presume RTAI and subsequently any task running on top of it are running
>   in user mode, as opposed to kernel mode?

Wrong. The real-time part of RTAI applications usually runs in kernel
mode; it may (but  does  not  have  to)  communicate  with  user-land
applications.

> - Would it be possible, using the RTAI, to receive inbound data encapsulated
>   in some storage protocal via the associate device driver, pass this about
>   a few RTAI tasks, and then ship it out encapsualted in another storage
>   protocal envelope via the associate device driver ... all the time using
>   the same buffer of I/O data (i.e. no buffer to buffer copies)??

Sure.

> Given our need to prevent buffer copies of I/O data, I was envisioning
> implementing a good part of our application as kernel treads. This is why I
> was looking into the preemption patch, and also why Real-Time abastraction
> layers that sit on top of the kernel were not showing up on my radar.

RTAI does not sit on top of linux, it's rather vice versa: Linux sits
on top of the RTAI "real-time kernel".

F'up to <rtai@rtai.org> ?


Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
If a train station is a place where a train stops,
                                           then what's a workstation?

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RE: Kernel Preemption patch

[brian.auld]

I would presume others interested in the information you posted below would
have the same questions:

(1) penguinppc.org patch page??
    - I don't remember, and couldn't find when double-checking, a link
      for patches at this url.

(2) source.mvista.com (440GP mmap patch)
    - I ncftp'ed to this location, and did not find any patches that
      were for the 440, including the mmap patch you mentioned. Is
      there a README somewhere that talks about this?

      Or, is this the pub/linuxppc/bigphys_remap... patch?

-- Brian

-----Original Message-----
From: Matt Porter [mailto:porter@cox.net]
Sent: Tuesday, February 25, 2003 8:24 AM
To: Eugene Surovegin
Cc: brian.auld@adic.com; linuxppc-embedded@lists.linuxppc.org
Subject: Re: Kernel Preemption patch

On Mon, Feb 24, 2003 at 02:29:18PM -0800, Eugene Surovegin wrote:
> I used George Anzinger patch (it looked less intrusive than 0(1) to me)
> with small fixes.
>
> Actually I applied 3 different patches to achieve reasonable user-mode
soft
> real-time for 440GP kernel:
>
> 1) preempt patch (from MVL)
> 2) rtsched by George Anzinger
> 3) lock-break by RML
>
> I can make a patch for 2.4.19 PPC devel tree snapshot with all those
> patches and my fixes if you want.
>
> I'm not sure whether I should post it to the list or not.

I think these things have generally wide interest.  I'm more than
willing to host them at source.mvista.com with the 440gp mmap patches
that are already there.

I suppose we should get a pointer from penguinppc.org's patch page
to this site.

Regards,
--
Matt Porter
porter@cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: Kernel Preemption patch

[Matt Porter]

On Tue, Feb 25, 2003 at 06:32:29AM -0800, brian.auld@adic.com wrote:
> I would presume others interested in the information you posted below would
> have the same questions:
>
> (1) penguinppc.org patch page??
>     - I don't remember, and couldn't find when double-checking, a link
>       for patches at this url.

http://penguinppc.org/dev/

> (2) source.mvista.com (440GP mmap patch)
>     - I ncftp'ed to this location, and did not find any patches that
>       were for the 440, including the mmap patch you mentioned. Is
>       there a README somewhere that talks about this?

It's mentioned in the changeset comments in the trees.

>       Or, is this the pub/linuxppc/bigphys_remap... patch?

Yes...that's the "mmap" patch.

--
Matt Porter
porter@cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

RE: Kernel Preemption patch

[brian.auld]

Eugene,

In a previous post, you mentioned that you had the Kernel Preemption patch
as well as the Real-Time scheduler patch running on a 2.4.19 kernel on
405/440 platforms...

I noticed that the Real-Time Scheduler patch 'closed shop' in May and has
suggested in the ingo-O2 patch as a replacement. Is this then the
"Real-Time" patch that you have applied to your 2.4.19 kernel?

If not, how did you manage to propogate forward George Anzinger's latest
patch (2.4.16) to your kernel?

Thanks,

Brian

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RE: Kernel Preemption patch

[Eugene Surovegin]

At 12:45 PM 2/24/2003, brian.auld@adic.com wrote:
>In a previous post, you mentioned that you had the Kernel Preemption patch
>as well as the Real-Time scheduler patch running on a 2.4.19 kernel on
>405/440 platforms...
>
>If not, how did you manage to propogate forward George Anzinger's latest
>patch (2.4.16) to your kernel?

I used George Anzinger patch (it looked less intrusive than 0(1) to me)
with small fixes.

Actually I applied 3 different patches to achieve reasonable user-mode soft
real-time for 440GP kernel:

1) preempt patch (from MVL)
2) rtsched by George Anzinger
3) lock-break by RML

I can make a patch for 2.4.19 PPC devel tree snapshot with all those
patches and my fixes if you want.

I'm not sure whether I should post it to the list or not.

Eugene


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Re: Kernel Preemption patch

[Stefan Roese]

Hi Eugene,

> Actually I applied 3 different patches to achieve reasonable
> user-mode soft
> real-time for 440GP kernel:
>
> 1) preempt patch (from MVL)
> 2) rtsched by George Anzinger
> 3) lock-break by RML
>
> I can make a patch for 2.4.19 PPC devel tree snapshot with all those
> patches and my fixes if you want.
>
> I'm not sure whether I should post it to the list or not.

I am interested in this patch too. If it is too big for this list, could you
please send it to me directly...

Best regards,
Stefan.


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Re: Kernel Preemption patch

[Matt Porter]

On Mon, Feb 24, 2003 at 02:29:18PM -0800, Eugene Surovegin wrote:
> I used George Anzinger patch (it looked less intrusive than 0(1) to me)
> with small fixes.
>
> Actually I applied 3 different patches to achieve reasonable user-mode soft
> real-time for 440GP kernel:
>
> 1) preempt patch (from MVL)
> 2) rtsched by George Anzinger
> 3) lock-break by RML
>
> I can make a patch for 2.4.19 PPC devel tree snapshot with all those
> patches and my fixes if you want.
>
> I'm not sure whether I should post it to the list or not.

I think these things have generally wide interest.  I'm more than
willing to host them at source.mvista.com with the 440gp mmap patches
that are already there.

I suppose we should get a pointer from penguinppc.org's patch page
to this site.

Regards,
--
Matt Porter
porter@cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: Kernel Preemption patch

[Matt Porter]

On Mon, Feb 24, 2003 at 02:29:18PM -0800, Eugene Surovegin wrote:
> I can make a patch for 2.4.19 PPC devel tree snapshot with all those
> patches and my fixes if you want.

Thanks.  I placed Eugene's patch at ftp://source.mvista.com/pub/linuxppc/

There should be a pointer from penguinppc.org to this site in the
near future.  Hopefully, that will make it more noticeable.

Regards,
--
Matt Porter
porter@cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: Kernel Preemption patch

[Eugene Surovegin]

At 08:18 PM 2/25/2003, Matt Porter wrote:

>I placed Eugene's patch at ftp://source.mvista.com/pub/linuxppc/

This patch is against 2.4.19 PPC devel kernel (bk cset 1.1091.1.23, 3rd of
August 2002).
It contains the following:

1) preempt kernel (preempt-kernel-rml-2.4.19-rc5-3.patch + MV fixes)
2) lock-break (lock-break-rml-2.4.18-1.patch)
3) rtsched (rtsched-2.4.16-1.0.patch + my fixes)
4) LTT (linux trace toolkit) (0.9.5a release)

Eugene


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Re: Kernel Preemption patch

[Matt Porter]

On Tue, Feb 25, 2003 at 08:25:33PM -0800, Eugene Surovegin wrote:
>
> At 08:18 PM 2/25/2003, Matt Porter wrote:
>
> >I placed Eugene's patch at ftp://source.mvista.com/pub/linuxppc/
>
> This patch is against 2.4.19 PPC devel kernel (bk cset 1.1091.1.23, 3rd of
> August 2002).
> It contains the following:
>
> 1) preempt kernel (preempt-kernel-rml-2.4.19-rc5-3.patch + MV fixes)
> 2) lock-break (lock-break-rml-2.4.18-1.patch)
> 3) rtsched (rtsched-2.4.16-1.0.patch + my fixes)
> 4) LTT (linux trace toolkit) (0.9.5a release)

Oops, yeah, well I just added this text to a README.pk-rtsched-ltt at
the site.  FWIW, I also added a README.biphys_remap to that patch to
and noted the originator of each.  If anybody sends additional useful
patches I'll try to do the same so they make sense 6 months from now. :)

Regards,
--
Matt Porter
porter@cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

RE: Kernel Preemption patch

[brian.auld]

Eugene,

Sorry, I'm using microsoft outlook and I can't seem to figure out how to
embedded comments in a satisfactory manner, so I have to write my replies at
the top of email threads all the time...

Below is an excerp from your post below. You include it to show the
redefinition of the line "#if !defined(CONFIG_4xx) || defined(CONFIG_440)".

However, I noticed that your 'preempt_enable' at the bottom of the exerp has
been changed from 'preempt_enable' as in the RML patch, to
'preempt_enable_no_reshed'. What's the reason for this inconsistency?

<----------------- cut ------------------->
#if !defined(CONFIG_4xx) || defined(CONFIG_440)
         case 0x900:
#else
         case 0x1000:
#endif
                 ret = timer_interrupt(regs);
                 break;
         default:
                 BUG();
         }

         preempt_enable_no_resched();
         return ret;
}
#endif /* CONFIG_PREEMPT */
<------------------ cut -------------------->

-- Brian

-----Original Message-----
From: Eugene Surovegin [mailto:ebs@ebshome.net]
Sent: Sunday, February 23, 2003 5:54 PM
To: brian.auld@adic.com
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: Kernel Preemption patch

At 02:28 PM 2/23/2003, brian.auld@adic.com wrote:
>Hello,
>
>Has anyone successfully applied and run the linux kernel preemption patch
on
>a 2.4.20 kernel. I have the following:
>
>- Latest Denx kernel (2_4_devel) running on 440GP ebony
>- 'preempt-kernel-rml-2.4.20-1.patch' applied to my kernel source
>   (I manually corrected a couple of fails and double checked a few
>    'successfully applied with fuzz' instances when applying the patch).
>- Kernel compiled with 'Kernel preemption =y' in make oldconfig
>
>When I try to boot this kernel, I get the following error:
>
><------- snipped
>Kernel command line: root=/dev/nfs rw
>nfsroot=172.16.77.152:/opt/eldk/ppc_4xx
>ip=172.16.77.155:172.16.77.152::255.255.255.0:EBONY-2::off
>kernel BUG at irq.c:575!
>Oops: Exception in kernel mode, sig: 4
>NIP: C0002B04 XER: 00000000 LR: C0002B04 SP: C0125F50 REGS: c0125ea0 TRAP:
>0700    Not tainted
>MSR: 00001030 EE: 0 PR: 0 FP: 0 ME: 1 IR/DR: 11
>TASK = c0124060[0] 'swapper' Last syscall: 0
>last math 00000000 last altivec 00000000
>PLB0: bear= 0x00008000 acr=   0x9b000000 besr=  0x00000000
>
>GPR00: C0002B04 C0125F50 C0124060 00000019 00001030 00000001 00000020
>C0170000
>GPR08: 000001D8 00000002 00000000 C0125E70 C012A8A8 71000000 07FE7300
>007FFC73
>GPR16: 00000000 00000001 007FFC00 FFFFFFFF 00001032 C0125F60 00000000
>C00017CC
>GPR24: C0002AA0 007FFB90 00000E00 007FFC73 007FFC00 00000000 00000000
>007FFB90
>Call backtrace:
>C0002B04 C00017CC C0133504 C0000224
>Kernel panic: Attempted to kill the idle task!
>In idle task - not syncing
>  <0>Rebooting in 180 seconds..

RML patches doesn't support 2_4_devel tree very well (and especially
PPC440).

If irq.c:575 correspond to preempt_intercept function in your tree, it
should look like:

#ifdef CONFIG_PREEMPT
int
preempt_intercept(struct pt_regs *regs)
{
         int ret;

         preempt_disable();

         switch(regs->trap) {
         case 0x500:
                 ret = do_IRQ(regs);
                 break;
#if !defined(CONFIG_4xx) || defined(CONFIG_440)
         case 0x900:
#else
         case 0x1000:
#endif
                 ret = timer_interrupt(regs);
                 break;
         default:
                 BUG();
         }

         preempt_enable_no_resched();
         return ret;
}
#endif /* CONFIG_PREEMPT */


Please, note additional "defined(CONFIG_440)"

Eugene


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RE: Kernel Preemption patch

[Eugene Surovegin]

At 07:56 AM 2/24/2003, brian.auld@adic.com wrote:
>However, I noticed that your 'preempt_enable' at the bottom of the exerp has
>been changed from 'preempt_enable' as in the RML patch, to
>'preempt_enable_no_reshed'. What's the reason for this inconsistency?


Well, as I said I don't use RML patch. This code is from MVL.
Frankly, I don't think that this particular change is very important (maybe
it is :).
I didn't notice any difference between these two versions.

It's "if !defined(CONFIG_4xx) || defined(CONFIG_440)" which is more
important :)

Eugene


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Re: Kernel Preemption patch

[Todd Poynor]

At 07:56 AM 2/24/2003, brian.auld@adic.com wrote:

> However, I noticed that your 'preempt_enable' at the bottom of the
> exerp has
> been changed from 'preempt_enable' as in the RML patch, to
> 'preempt_enable_no_reshed'. What's the reason for this inconsistency?

The preempt_enable_no_reshed avoids a kernel stack overflow seen in
certain cases of heavy preemption, where each nested call to reschedule
on preemption is interrupted and again requests a preemption.  The
proper place to check for another preemption is at the top-level
interrupt/exception handler, so that we iterate and not recurse.

Oops, MontaVista needs to contribute this bug fix back to RML's public
patch, I'll put it on my list.


--
Todd


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RE: Kernel Preemption patch

[brian.auld]

Thanks,

My problem was I was searching this mailing list (linuxppc-embedded) instead
of linuxppc-dev.

Question: The MVL 2.1 tree ... where is this? This is not at bkbits, is it?
Do I require a MV subscription to use it?

-- Brian

-----Original Message-----
From: Eugene Surovegin [mailto:ebs@ebshome.net]
Sent: Sunday, February 23, 2003 6:05 PM
To: brian.auld@adic.com
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: Kernel Preemption patch

At 02:28 PM 2/23/2003, brian.auld@adic.com wrote:
>Has anyone successfully applied and run the linux kernel preemption patch
on
>a 2.4.20 kernel. I have the following:
>
>- Latest Denx kernel (2_4_devel) running on 440GP ebony
>- 'preempt-kernel-rml-2.4.20-1.patch' applied to my kernel source
>   (I manually corrected a couple of fails and double checked a few
>    'successfully applied with fuzz' instances when applying the patch).

Please, search mailing list archives.
There was some discussion about RML patches about a month ago.

In particular, there were some bugs/typos in PPC part.
Also I had problems on 440GP, and corrected them by using MVL 2.1 tree, not
RML patches.

Eugene.

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RE: Kernel Preemption patch

[Eugene Surovegin]

At 07:38 AM 2/24/2003, brian.auld@adic.com wrote:
>Question: The MVL 2.1 tree ... where is this? This is not at bkbits, is it?
>Do I require a MV subscription to use it?

I don't know.

There are a lot of MV people on this list.
I think they can answer this question better than me :)))

Eugene


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Re: Kernel Preemption patch

[Matt Porter]

On Mon, Feb 24, 2003 at 07:38:04AM -0800, brian.auld@adic.com wrote:
> Question: The MVL 2.1 tree ... where is this? This is not at bkbits, is it?
> Do I require a MV subscription to use it?

You can always get it from a MontaVista Linux Preview Kit for your
system.  http://www.mvista.com/previewkit/index.html

Regards,
--
Matt Porter
porter@cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

RE: Kernel Preemption patch

[brian.auld]

Thanks for the help.

What's with RML? Does that stand for Robert M Love (just a guess)?

I did search the list archives but was searching on "kernel preemption/ive
patch" which didn't give me any hits.

Do people typically search this mailing list archives via the web link at
penguinppc.org? That's what I use.

-- Brian

-----Original Message-----
From: Allen Curtis [mailto:acurtis@onz.com]
Sent: Sunday, February 23, 2003 5:34 PM
To: brian.auld@adic.com; linuxppc-embedded@lists.linuxppc.org
Subject: RE: Kernel Preemption patch

> Has anyone successfully applied and run the linux kernel
> preemption patch on
> a 2.4.20 kernel. I have the following:
>
> - Latest Denx kernel (2_4_devel) running on 440GP ebony
> - 'preempt-kernel-rml-2.4.20-1.patch' applied to my kernel source
>   (I manually corrected a couple of fails and double checked a few
>    'successfully applied with fuzz' instances when applying the patch).
> - Kernel compiled with 'Kernel preemption =y' in make oldconfig

Yes, but didn't you get any compile errors? There are some missing brackets,
etc. to fix. Check the attached message from this list.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Kernel Preemption patch

[brian.auld]

Hello,

Has anyone successfully applied and run the linux kernel preemption patch on
a 2.4.20 kernel. I have the following:

- Latest Denx kernel (2_4_devel) running on 440GP ebony
- 'preempt-kernel-rml-2.4.20-1.patch' applied to my kernel source
  (I manually corrected a couple of fails and double checked a few
   'successfully applied with fuzz' instances when applying the patch).
- Kernel compiled with 'Kernel preemption =y' in make oldconfig

When I try to boot this kernel, I get the following error:

<------- snipped
Kernel command line: root=/dev/nfs rw
nfsroot=172.16.77.152:/opt/eldk/ppc_4xx
ip=172.16.77.155:172.16.77.152::255.255.255.0:EBONY-2::off
kernel BUG at irq.c:575!
Oops: Exception in kernel mode, sig: 4
NIP: C0002B04 XER: 00000000 LR: C0002B04 SP: C0125F50 REGS: c0125ea0 TRAP:
0700    Not tainted
MSR: 00001030 EE: 0 PR: 0 FP: 0 ME: 1 IR/DR: 11
TASK = c0124060[0] 'swapper' Last syscall: 0
last math 00000000 last altivec 00000000
PLB0: bear= 0x00008000 acr=   0x9b000000 besr=  0x00000000

GPR00: C0002B04 C0125F50 C0124060 00000019 00001030 00000001 00000020
C0170000
GPR08: 000001D8 00000002 00000000 C0125E70 C012A8A8 71000000 07FE7300
007FFC73
GPR16: 00000000 00000001 007FFC00 FFFFFFFF 00001032 C0125F60 00000000
C00017CC
GPR24: C0002AA0 007FFB90 00000E00 007FFC73 007FFC00 00000000 00000000
007FFB90
Call backtrace:
C0002B04 C00017CC C0133504 C0000224
Kernel panic: Attempted to kill the idle task!
In idle task - not syncing
 <0>Rebooting in 180 seconds..
---------> the end

-- Brian

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

RE: Kernel Preemption patch

[Allen Curtis]

[-- Attachment #1: Type: text/plain, Size: 593 bytes --]

> Has anyone successfully applied and run the linux kernel
> preemption patch on
> a 2.4.20 kernel. I have the following:
>
> - Latest Denx kernel (2_4_devel) running on 440GP ebony
> - 'preempt-kernel-rml-2.4.20-1.patch' applied to my kernel source
>   (I manually corrected a couple of fails and double checked a few
>    'successfully applied with fuzz' instances when applying the patch).
> - Kernel compiled with 'Kernel preemption =y' in make oldconfig

Yes, but didn't you get any compile errors? There are some missing brackets,
etc. to fix. Check the attached message from this list.

[-- Attachment #2: Type: message/rfc822, Size: 2498 bytes --]

From: "Eugene Surovegin" <ebs@innocent.com>
To: "Joakim Tjernlund" <Joakim.Tjernlund@lumentis.se>
Cc: <linuxppc-dev@lists.linuxppc.org>
Subject: Re: Is the preemptive kernel patch unsafe for 8xx/PPC?
Date: Thu, 12 Dec 2002 22:09:48 -0800
Message-ID: <5.1.0.14.2.20021212214102.02bf1338@mail.attbi.com>


Joakim,

At 12:35 PM 12/12/2002, you wrote:
>Was that the 2.4.19-2 patch? What were the bugs and have you fixed them?

I had the following issues with 2.4.19-2 (2.4.20-1 is identical in this
regard):

1) arch/ppc/kernel.entry.S

diff -urN linux-2.4.20/arch/ppc/kernel/entry.S linux/arch/ppc/kernel/entry.S
--- linux-2.4.20/arch/ppc/kernel/entry.S        2002-11-28
18:53:11.000000000 -0500
+++ linux/arch/ppc/kernel/entry.S       2002-12-11 02:34:47.000000000 -0500
@@ -278,6 +278,41 @@
          */
         cmpi    0,r3,0
         beq     restore
+#ifdef CONFIG_PREEMPT
+       lwz     r3,PREEMPT_COUNT(r2)
+       cmpi    0,r3,1
+       bge     ret_from_except
+       lwz     r5,_MSR(r1)
+       andi.   r5,r5,MSR_PR
+       bne     do_signal_ret

     <rest of the diff is skipped>

I had to change the last command to "bne ret_from_except".
I checked MontaVista tree, and they have "ret_from_except" there also.

Without this change trivial code:

   while (true) ;

locked the box completely.

2) include/asm-ppc/pgalloc.h  There are curly brackets missing in
get_pgd_fast()

3) to support 440GP you have to modify
arc/ppc/kernel/irc.c:preempt_intercept:

#if !defined(CONFIG_4xx) || defined(CONFIG_440)
         case 0x900:
#else
         case 0x1000:
#endif

With these changes (an maybe some others I forgot to mention here :),
I have pretty stable preemptable kernel (2.4.19, PPC440GP & 405GP, also
with rtsched patch by George Anzinger)

Thanks,


  Eugene Surovegin <mailto:ebs@innocent.com>

Re: Kernel Preemption patch

[Eugene Surovegin]

At 02:28 PM 2/23/2003, brian.auld@adic.com wrote:
>Hello,
>
>Has anyone successfully applied and run the linux kernel preemption patch on
>a 2.4.20 kernel. I have the following:
>
>- Latest Denx kernel (2_4_devel) running on 440GP ebony
>- 'preempt-kernel-rml-2.4.20-1.patch' applied to my kernel source
>   (I manually corrected a couple of fails and double checked a few
>    'successfully applied with fuzz' instances when applying the patch).
>- Kernel compiled with 'Kernel preemption =y' in make oldconfig
>
>When I try to boot this kernel, I get the following error:
>
><------- snipped
>Kernel command line: root=/dev/nfs rw
>nfsroot=172.16.77.152:/opt/eldk/ppc_4xx
>ip=172.16.77.155:172.16.77.152::255.255.255.0:EBONY-2::off
>kernel BUG at irq.c:575!
>Oops: Exception in kernel mode, sig: 4
>NIP: C0002B04 XER: 00000000 LR: C0002B04 SP: C0125F50 REGS: c0125ea0 TRAP:
>0700    Not tainted
>MSR: 00001030 EE: 0 PR: 0 FP: 0 ME: 1 IR/DR: 11
>TASK = c0124060[0] 'swapper' Last syscall: 0
>last math 00000000 last altivec 00000000
>PLB0: bear= 0x00008000 acr=   0x9b000000 besr=  0x00000000
>
>GPR00: C0002B04 C0125F50 C0124060 00000019 00001030 00000001 00000020
>C0170000
>GPR08: 000001D8 00000002 00000000 C0125E70 C012A8A8 71000000 07FE7300
>007FFC73
>GPR16: 00000000 00000001 007FFC00 FFFFFFFF 00001032 C0125F60 00000000
>C00017CC
>GPR24: C0002AA0 007FFB90 00000E00 007FFC73 007FFC00 00000000 00000000
>007FFB90
>Call backtrace:
>C0002B04 C00017CC C0133504 C0000224
>Kernel panic: Attempted to kill the idle task!
>In idle task - not syncing
>  <0>Rebooting in 180 seconds..

RML patches doesn't support 2_4_devel tree very well (and especially PPC440).

If irq.c:575 correspond to preempt_intercept function in your tree, it
should look like:

#ifdef CONFIG_PREEMPT
int
preempt_intercept(struct pt_regs *regs)
{
         int ret;

         preempt_disable();

         switch(regs->trap) {
         case 0x500:
                 ret = do_IRQ(regs);
                 break;
#if !defined(CONFIG_4xx) || defined(CONFIG_440)
         case 0x900:
#else
         case 0x1000:
#endif
                 ret = timer_interrupt(regs);
                 break;
         default:
                 BUG();
         }

         preempt_enable_no_resched();
         return ret;
}
#endif /* CONFIG_PREEMPT */


Please, note additional "defined(CONFIG_440)"

Eugene


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Re: Kernel Preemption patch

[Eugene Surovegin]

At 02:28 PM 2/23/2003, brian.auld@adic.com wrote:
>Has anyone successfully applied and run the linux kernel preemption patch on
>a 2.4.20 kernel. I have the following:
>
>- Latest Denx kernel (2_4_devel) running on 440GP ebony
>- 'preempt-kernel-rml-2.4.20-1.patch' applied to my kernel source
>   (I manually corrected a couple of fails and double checked a few
>    'successfully applied with fuzz' instances when applying the patch).

Please, search mailing list archives.
There was some discussion about RML patches about a month ago.

In particular, there were some bugs/typos in PPC part.
Also I had problems on 440GP, and corrected them by using MVL 2.1 tree, not
RML patches.

Eugene.


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