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Old 03-15-2012, 11:30 AM
Tim Gardner
 
Default Drop Non-smp PowerPC Kernel Flavor

On 03/15/2012 06:02 AM, Colin Watson wrote:

On Thu, Mar 15, 2012 at 11:02:09AM +0800, Jeremy Kerr wrote:

Hi all,

We consulted Jeremy Kerr about this. He says that an SMP kernel will run
on all 32 bit powerpc platforms, including non-SMP.


To clarify: the hardware supported by the powerpc and powerpc-smp
flavours is almost identical. The differences probably don't matter
Ubuntu users, as it'll be obscure hardware. I've CC-ed benh in case
he wants to correct me on this one.

However, the SMP kernel supports (surprise!) bringing up>1 CPU on
machines that have>1 CPU. With a UP kernel on these machines, the
other CPUs are left doing nothing.

The main class of 32-bit SMP powerpc machines are the Apple dual-G4s.

So, since the hardware coverage is essentially the same, but we get
SMP support on SMP machines, I'd say that we would prefer the
powerpc-smp kernel over the powerpc flavour.


OK, that all makes sense, and I agree based on that. I'd forgotten
about the dual G4 class.

I would switch the installer over to powerpc-smp today, then, except
that the kernel doesn't ship powerpc-smp udebs yet, only powerpc and
powerpc64-smp. Can somebody fix that so that I can do this transition?



I'll take care of it. Leann plans to upload later in her day Friday, so
the kernel ought to be available by Monday.


rtg
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Old 03-15-2012, 09:06 PM
Patrick Kevin McCaffrey
 
Default Drop Non-smp PowerPC Kernel Flavor

The only Apple PowerPC machines that can use the 64-bit image are the G5's (but I believe they could also use the standard SMP one).

Honestly, I don't think we can really drop any of the kernels. Any dual processor machine is going to use the SMP kernel (and there's a lot of dual processor G4's out there...), and any single processor machine needs the non-smp kernel, right? So, wouldn't dropping any of them mean dropping support one of following: single processor machines, SMP support, or 64-bit support.

I guess if you HAD to get rid of one, I'd argue for the 64 bit one. As I stated, only the G5's can use the 64 bit kernel...

----- Original Message -----
From: "Leann Ogasawara" <leann.ogasawara@canonical.com>
To: "Colin Watson" <cjwatson@ubuntu.com>
Cc: "kernel-team" <kernel-team@lists.ubuntu.com>, lubuntu-users@lists.ubuntu.com, "ubuntu-devel" <ubuntu-devel@lists.ubuntu.com>
Sent: Wednesday, March 14, 2012 1:01:59 PM
Subject: Re: [RFC] Drop Non-smp PowerPC Kernel Flavor

On Wed, 2012-03-14 at 17:00 +0000, Colin Watson wrote:
> On Wed, Mar 14, 2012 at 09:52:01AM -0700, Leann Ogasawara wrote:
> > The Ubuntu Kernel Team has been evaluating some of the current
> > maintenance burdens for the upcoming Precise Pangolin 12.04 LTS release.
> > One area which would reduce the maintenance costs would be to drop the
> > non-smp PowerPC kernel flavor. There are currently three PowerPC
> > flavors:
>
> Making the associated installer changes shouldn't be a big deal, but I
> suggest you ask the Xubuntu and Lubuntu communities about this since a
> good proportion of powerpc users are there.

Adding lubuntu-users and Julien Lavergne to the discussion to get their
feedback regarding the impact on Lubuntu users.

As Micah noted, Xubuntu stopped producing PowerPC images due to a lack
of testers.

> > * non-smp (linux-image-powerpc)
> > * smp (linux-image-powerpc-smp)
> > * smp-64 (linux-image-powerpc64-smp)
>
> It's not clear to me whether it would make more sense to drop -powerpc
> or -powerpc-smp. My memory is that -powerpc-smp was significantly less
> used and would be a better candidate for removal. Do you have notes on
> which hardware is covered by -powerpc-smp that can't use -powerpc64-smp?
>
> --
> Colin Watson [cjwatson@ubuntu.com]
>



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Old 03-16-2012, 08:24 AM
o jordan
 
Default Drop Non-smp PowerPC Kernel Flavor

I picked up this discussion from the lubuntu-qa list.* *The non-smp kernel I would say is by far the most used of the PowerPC kernels.* In fact, I would guess most dual-G4 users are unaware of the smp kernel.* When I re-wrote the PowerPC FAQ in January I added something about SMP to try and make people aware of it https://wiki.ubuntu.com/PowerPCFAQ#G4_Dual-processor_systems .* I've been reading the Apple forum for a year and I think the 32 bit SMP kernel has only been mentioned once?
*
However, if one kernel has to go then I guess the non-smp has to be the one.* Loosing support of a processor is far worse than a 1-2% hit.* Even if there are probably very few dual-G4 users.* I know other PowerPC users disagree with me on this https://lists.launchpad.net/lubuntu-qa/msg00454.html*.
*
Colin, if you are messing around with the kernels on the installer can you look into a problem with the vmlinux and initrd symbollic links being placed in the root directory instead of /boot?* I'll file a proper bug on it when I have all the info to hand, but it is only a problem with the desktop cds.* Thanks*
*
Micah, I'll test a xubuntu desktop cd.* I'm resisting dropping down to lubuntu, but 12.04 Ubuntu is too heavy for my iBook now (10.04 is great).* For the moment I'm installing xubuntu via a cli start.
*
This is the current list of outstanding issues with 12.04 on PowerPC that I've come across: https://wiki.ubuntu.com/PowerPCKnownIssues#A12.04_Precise_Pangolin .* Leann fixed a problem with nvram - Thanks!* There is one outstanding kernel issue regarding the ATI framebuffers.* Hopefully you can understand my ramble!* Cheers
*
*
Adam
*
*
*

*
*
*
On 03/14/2012 12:00 PM, Colin Watson wrote:
> On Wed, Mar 14, 2012 at 09:52:01AM -0700, Leann Ogasawara wrote:
>> The Ubuntu Kernel Team has been evaluating some of the current
>> maintenance burdens for the upcoming Precise Pangolin 12.04 LTS release.
>> One area which would reduce the maintenance costs would be to drop the
>> non-smp PowerPC kernel flavor. There are currently three PowerPC
>> flavors:
> Making the associated installer changes shouldn't be a big deal, but I
> suggest you ask the Xubuntu and Lubuntu communities about this since a
> good proportion of powerpc users are there.
>
Xubuntu stopped producing PowerPC images due to a lack of testers.* If
there's interest in these, and people committed to testing, they could
be reinstated.

Thanks,
Micah





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Old 03-18-2012, 06:41 PM
Adam Conrad
 
Default Drop Non-smp PowerPC Kernel Flavor

On Wed, Mar 14, 2012 at 10:39:42AM -0700, Leann Ogasawara wrote:
>
> Jeremy Kerr did some testing a while back and noted that the PowerPC smp
> flavor should run on non-smp hardware, but did acknowledge there could
> be a slight performance degradation.

For the record, the powerpc-smp kernel doesn't boot AT ALL on my G3
PowerMac. Doesn't even get far enough to init video of any sort, so
I can't tell you what the problem is.

I'm downloading the source right now, but I have a sneaking suspicion
that, perhaps, our powerpc-smp kernel is built for >= G4 (since that
was the first PPC32 SMP hardware anyone cared about), and thus won't
boot on any older CPUs.

... Adam

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Old 03-19-2012, 01:13 AM
Jeremy Kerr
 
Default Drop Non-smp PowerPC Kernel Flavor

Hi Adam,


For the record, the powerpc-smp kernel doesn't boot AT ALL on my G3
PowerMac. Doesn't even get far enough to init video of any sort, so
I can't tell you what the problem is.

I'm downloading the source right now, but I have a sneaking suspicion
that, perhaps, our powerpc-smp kernel is built for>= G4 (since that
was the first PPC32 SMP hardware anyone cared about), and thus won't
boot on any older CPUs.



It should boot - there's nothing specific that excludes pre-G4 machines
in this configuration. Could you let me know:


* which kernel version (precise) that you're trying to boot
* more details about the machine

?

Cheers,


Jeremy

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Old 03-19-2012, 01:20 AM
Jeremy Kerr
 
Default Drop Non-smp PowerPC Kernel Flavor

Hi Patrick,


The only Apple PowerPC machines that can use the 64-bit image are the
G5's



Plus the PS3.


(but I believe they could also use the standard SMP one).



We only have one flavour of the 64-bit kernel, and it's SMP.



Honestly, I don't think we can really drop any of the kernels. Any
dual processor machine is going to use the SMP kernel (and there's a
lot of dual processor G4's out there...), and any single processor
machine needs the non-smp kernel, right?



No, single processor machines should be able to use the SMP kernel.


So, wouldn't dropping any
of them mean dropping support one of following: single processor
machines, SMP support, or 64-bit support.



The idea here is that we should be able to drop the 32-bit UP kernel
without losing any machine support.


Cheers,


Jeremy

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Old 03-19-2012, 01:26 AM
Adam Conrad
 
Default Drop Non-smp PowerPC Kernel Flavor

On Mon, Mar 19, 2012 at 10:13:52AM +0800, Jeremy Kerr wrote:
>
> It should boot - there's nothing specific that excludes pre-G4
> machines in this configuration. Could you let me know:

I appreciate your optimism, but it most certainly doesn't boot.
Andy and I have been going over it, and we're wondering if perhaps
it's the CONFIG_NEED_PER_CPU_KM bit, which is mutually exclusive
with CONFIG_SMP.

> * which kernel version (precise) that you're trying to boot

linux-image-3.2.0-19-powerpc-smp (3.2.0-19.30) won't boot.
linux-image-3.2.0-18-powerpc (3.2.0-18.29) works just fine.

> * more details about the machine

It's an OldWorld Beige G3 with one of the many 1GHz upgrade
boards that were popular long ago, sadly, I don't recall
which brand/model, though I suspect I'd have the same
problem booting if I dug up the original CPU and stuck it
back in.

I'm not entirely sure what more info you might want than
"OldWorld G3 Tower", but if there's something specific you'd
like me digging for, I'm all ears.

... Adam

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Old 03-19-2012, 01:35 AM
Adam Conrad
 
Default Drop Non-smp PowerPC Kernel Flavor

On Thu, Mar 15, 2012 at 05:06:28PM -0500, Patrick Kevin McCaffrey wrote:
>
> I guess if you HAD to get rid of one, I'd argue for the 64 bit one. As I
> stated, only the G5's can use the 64 bit kernel...

We support a lot more than just Apple hardware (where do people get this
impression from?) and dropping the 64-bit kernel would be dropping support
for a host of POWER5 and above systems.

... Adam

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Old 03-19-2012, 01:47 AM
Jeremy Kerr
 
Default Drop Non-smp PowerPC Kernel Flavor

Hi Benh,

Any ideas about this? SMP kernel is not booting on an OldWorld G3, while
UP works fine; only major difference is CONFIG_SMP, but here is the
delta between the split configs:


--- debian.master/config/powerpc/config.flavour.powerpc
+++ debian.master/config/powerpc/config.flavour.powerpc-smp
@@ -8 +8 @@
-# CONFIG_CFG80211_REG_DEBUG is not set
+CONFIG_CFG80211_REG_DEBUG=y
@@ -15 +15 @@
-# CONFIG_GENERIC_TBSYNC is not set
+CONFIG_GENERIC_TBSYNC=y
@@ -19,2 +19,2 @@
-CONFIG_KGDB=y
-CONFIG_LATENCYTOP=y
+# CONFIG_KGDB is not set
+# CONFIG_LATENCYTOP is not set
@@ -24 +24 @@
-# CONFIG_MUTEX_SPIN_ON_OWNER is not set
+CONFIG_MUTEX_SPIN_ON_OWNER=y
@@ -26,0 +27 @@
+CONFIG_NR_CPUS=4
@@ -40 +41,2 @@
-CONFIG_SCHEDSTATS=y
+CONFIG_RCU_FANOUT=32
+# CONFIG_SCHEDSTATS is not set
@@ -42,2 +44,2 @@
-# CONFIG_SMP is not set
-CONFIG_TPS65010=m
+CONFIG_SMP=y
+# CONFIG_TPS65010 is not set


[I can send the full generated configs if it helps]



It should boot - there's nothing specific that excludes pre-G4
machines in this configuration. Could you let me know:


I appreciate your optimism, but it most certainly doesn't boot.
Andy and I have been going over it, and we're wondering if perhaps
it's the CONFIG_NEED_PER_CPU_KM bit, which is mutually exclusive
with CONFIG_SMP.


* which kernel version (precise) that you're trying to boot


linux-image-3.2.0-19-powerpc-smp (3.2.0-19.30) won't boot.
linux-image-3.2.0-18-powerpc (3.2.0-18.29) works just fine.


* more details about the machine


It's an OldWorld Beige G3 with one of the many 1GHz upgrade
boards that were popular long ago, sadly, I don't recall
which brand/model, though I suspect I'd have the same
problem booting if I dug up the original CPU and stuck it
back in.

I'm not entirely sure what more info you might want than
"OldWorld G3 Tower", but if there's something specific you'd
like me digging for, I'm all ears.



Cheers,


Jeremy

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Old 03-19-2012, 01:52 AM
Jeremy Kerr
 
Default Drop Non-smp PowerPC Kernel Flavor

Hi Patrick,


Plus the PS3.



... and a host of other 64-bit platforms:

CONFIG_PPC_BOOK3S=y
CONFIG_PPC_BOOK3S_64=y
CONFIG_PPC_MAPLE=y
CONFIG_PPC_PASEMI=y
CONFIG_PPC_PMAC64=y
CONFIG_PPC_POWERNV=y
CONFIG_PPC_PS3=y
CONFIG_PPC_PSERIES=y
CONFIG_PPC_CELL=y

Cheers,


Jeremy



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