# Initial 2.6.28 problems

## Cyker

Just made the big jump from 2.6.24 to 2.6.28, running into a few initial issues:

1) Loss of NCQ support with sata_nv driver; Getting the ol': 

```
ata4.00: 1953525168 sectors, multi 16: LBA48 NCQ (depth 0/32)
```

 problem (It should say depth 31/32)

Any idea how to fix this? It is causing noticable ('tho not crippling) slowdown during heavy accesses. I don't know if it is a bug or just something I need to set (The config between 2.6.24 and 2.6.28 has changed significantly, to the point that make oldconfig required a large amount of intervention and tweaking. It may be that there is a new option for NCQ stuff somewhere that I have missed/can't see/find)

2) Missing /sys/devices/system/cpu/sched_mc_power_savings

Either I missed some kernel option due to the config layout changes as mentioned above, or it has been moved somewhere. Anyone able to shed any light on this?

3) What does this mean at the top of dmesg:

```
KERNEL supported cpus:

  Intel GenuineIntel

  AMD AuthenticAMD

  NSC Geode by NSC

  Cyrix CyrixInstead

  Centaur CentaurHauls

  Transmeta GenuineTMx86

  Transmeta TransmetaCPU

  UMC UMC UMC UMC

```

The kernel config is set to K8 and the make.conf buld environment is set to -march=k8, so unless something has been changed from march to mtune, I don't see how all these CPUs could work on this kernel. Is there any way (or point) in trying to eliminate all these for the sake of keeping the kernel small?

Or is the kernel just being more verbose for some reason, and that I should ignore this?

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## blueflame

Not that this helps you, but ... I'm running 2.6.25-r9 and I have the same "problem" as you - can't say I've noticed any performance issues though.

```
ata2.00: 1953525168 sectors, multi 1: LBA48 NCQ (depth 0/32)
```

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## Cyker

I don't suppose you know if it worked for you in 2.6.24?

The only noted changes I can find is that something called swncq is now enabled by default on th sata_nv driver which was disabled by default in <=.24

In the older .24 kernel when it worked, the driver reported going into ADMA mode, but this is missing from the newer kernels.

I'm trying to find how to re-enable ADMA and force swncq to be off, but these appear to be undocumented in the kernel docs. Grepping the source...

Currently I am mitigating the performance loss by mounting the fs as ext4  :Razz: 

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## Paczesiowa

how about fbsplash? it looks much worse than in 27, it flickers during boot, and mostly disappears until init kicks in

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## Cyker

Ah, apparently ADMA was disabled due to concerns about problems with it; I found this in bugs.gentoo.org

https://bugs.gentoo.org/232107

I can force ADMA on by sticking sata_nv.adma=1 on the grub command line, and NCQ works again!

However, I have experienced the disconnection errors they mention, and while it hasn't caused my RAID array to die, I don't think I want to risk. The performance loss isn't massive, and is offset by ext4 and me switching down from full journalling in order get the delayed transaction stuff to work...

Also, with journal_checksumming enabled I can get rid of barriers so that should boost speed quite a lot!

Still haven't worked out where /sys/devices/system/cpu/sched_mc_power_savings has gone 'tho...

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## ZeuZ_NG

Looks like the rush to release and the fever of "version-itis" has brought us all to some unwanted troubles... 

Me, personally, Have had to stick with 2.6.24 as well since its the last kernel that works without too much problems on my system...

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## paulbiz

My sata_nv has depth 31/32 for all of my SATA drives in 2.6.28 -- without any special kernel options.

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## energyman76b

wtf 'rushed'???

they turned off adma per default because it eats data - a long time ago and because the problem is deep in the nvidia hardware. If someone 'rushed' a release it was nvidia. You should be glad the dangerous option is off.

And if you have it still on with later releases - well maybe your chip is not affected?

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## ZeuZ_NG

 *energyman76b wrote:*   

> wtf 'rushed'???
> 
> they turned off adma per default because it eats data - a long time ago and because the problem is deep in the nvidia hardware. If someone 'rushed' a release it was nvidia. You should be glad the dangerous option is off.
> 
> And if you have it still on with later releases - well maybe your chip is not affected?

 

Well yeah, the problem IS nvidia, though, I wasnt talking at any place of adma.

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## energyman76b

then don't stick with 2.6.24 - because there is a reason they turned it off.

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## ZeuZ_NG

 *energyman76b wrote:*   

> then don't stick with 2.6.24 - because there is a reason they turned it off.

 

I stick with it because it's the last kernel with wich my system doesn't turn unstable.

That's the only reason.

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