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Installation - Problems disabling DMA

pcalvert - 06.09.2006, 00:42 Uhr
Titel: Problems disabling DMA
I have an old laptop that requires that ACPI and DMA (mainly DMA) be disabled. The problem is that Kanotix (2005-04) seems to insist on enabling DMA even after I have told it not to use DMA.

I booted the Kanotix CD with the acpi=off and nodma options. That seemed to work fine. However, when I installed Kanotix to the HDD the disabling of DMA did not carry through. Here is the relevant part of my lilo.conf file:

Code:

image=/boot/vmlinuz
        label="Linux"
        initrd=/boot/initrd.img
        append="ramdisk_size=100000 lang=us apm=power-off nomce acpi=off "
        read-only


As you can see, DMA is not being disabled. So I will have to manually correct this before attempting to boot the HDD-installed Kanotix by editing lilo.conf and running lilo again (by running the installer again and telling it to repair the installation).

Also, I am a bit confused as to why Kanotix uses "nodma" since that appears to non-standard. Debian stable, for example, uses "ide=nodma".

Finally, it appears that even adding "nodma" or "ide=nodma" may not be enough to disable DMA. When I originally installed Kanotix, I could not successfully boot the system unless I also disabled DMA by adding this to the end of the hdparm.conf file:

Code:

command_line {
       hdparm -d0 /dev/hda
}


Then I opened a root shell and typed these commands:

Code:

mount -o dev /media/hdaX
chroot /media/hdaX unfreeze-rc.d
chroot /media/hdaX update-rc.d hdparm defaults
chroot /media/hdaX freeze-rc.d

(Note: The "X" in "hdaX" above is the HDD partition on which Kanotix was installed.)


There is a possibility that I made a mistake, and that I don't actually have to go to the trouble of disabling DMA using hdparm. But I am fairly certain that I tried different ways of entering "nodma" and "ide=nodma" into the lilo.conf file, and the only thing that finally worked to completely disable DMA was to also disable it in the hdparm.conf file.

I reinstalled Kanotix today so I can try it again. If I disable DMA again with a kernel option in lilo.conf and Kanotix still tries to use DMA, then we will know that there is a bug.

Phil
Kano - 06.09.2006, 00:51 Uhr
Titel: RE: Problems disabling DMA
Kanotix kernels enable DMA by default. Maybe try hda=nodma, not sure if it can work.
pcalvert - 06.09.2006, 02:13 Uhr
Titel: Re: Problems disabling DMA
Kano hat folgendes geschrieben::
Kanotix kernels enable DMA by default. Maybe try hda=nodma, not sure if it can work.


What about Debian stable? Because that is what I am using now and all I did was add ide=nodma to the proper lines in lilo.conf and that was sufficient. No messing around with hdparm was necessary. Actually, I may not have had to add them. I don't clearly remember if I did or not. It's possible that Debian added it for me.

It seems to me that forcing DMA to be enabled by default is a bad idea. Enabling DMA after installation is easy for those who want it to be enabled. But if a system cannot reliably support DMA, then it is a lot more trouble to disable it because the HDD-installed Kanotix cannot be booted to fix the problem. One must have another Linux distro already installed or use a live CD to do the repair work.

Phil
slam - 06.09.2006, 08:30 Uhr
Titel: Re: Problems disabling DMA
Kanotix is optimized for modern hardware, and not a refugee camp for giving new life to old hardware (which is a nice task, too - but not ours). There are other distributions specialized for that: DSL, Vector, Puppy are probably the most well known. We enable DMA and ACPI by default because ALL desktop and laptop systems support it since several years, and need it for full functionality. For the same reason we default to Grub, Lilo is outdated and not on our list of watched and maintained applications. If you insist on using it, you will need to do some manual configuration work.

Said that, Kanotix is still very useful on old hardware, if one knows how to do manual adaption. For older hardware we have a quite extensive boot menu at the live CD, which enables you to run and install Kanotix on such. Please understand also, that Kanotix does not use Debian kernels, and therefore cheat codes known from Debian Stable might not work here. Please find a complete list of supported cheat codes for Kanotix kernels here: http://kanotix.com/FAQ-id_cat-63.html#q245. If the stock Kanotix kernel does not fit your needs we always offer different variants here: http://debian.tu-bs.de/project/kanotix/kernel/.

Alternatively you may use the existing config of the Kanotix kernel, adapt it to your special needs and re-compile it. Some people even successfully run Debian kernels on Kanotix. Please understand however, that we cannot guarantee for functionality in such case, and of course our ability to support you will be limited.

Several people here happily run Kanotix on old PII-350 to PIII-500 notebooks, with memory starting at 128Mb (even 64Mb is possible with limitations). If you don't insist on KDE, Gnome, OpenOffice and Firefox you will still have a snappy and reactive system with Kanotix on such hardware.

Defaults are, what they are: A compromise to fit the most. So please don't expect us to change DMA defaults, just to make installation easier for a few people, while giving bad performance to most others. We will always have an eye on not closing out completely owners of old hardware, but our focus is on the bleeding edge.

Thanks for understanding!

Greetings,
Chris
Kano - 06.09.2006, 08:32 Uhr
Titel: RE: Re: Problems disabling DMA
For me DMA is a requirement for hardware. I will not drop DMA auto mode for 1% or less of bad systems. These can use another kernel. You are free to install Debian ones via apt-get.
pcalvert - 06.09.2006, 16:43 Uhr
Titel: Re: Problems disabling DMA
Kano hat folgendes geschrieben::
Kanotix kernels enable DMA by default. Maybe try hda=nodma, not sure if it can work.


I think there may be some mis-communication going on here, so I want to reply to this message again.

Let me see if I understand what you are telling me. You are saying that Kanotix kernels have DMA enabled by default. In addition, no method is provided for turning it off because it is assumed that most modern hardware supports DMA. Is that correct?

Phil
Kano - 06.09.2006, 18:19 Uhr
Titel: RE: Re: Problems disabling DMA
nodma cheat in live mode disables DMA on the fly, but for HD install you have to use kernel cheats. When those don't work then there is no way and I will not worry about this at all because there are systems that can only use DMA when enabled the way it is currently and not afterwards.
slam - 06.09.2006, 18:49 Uhr
Titel: RE: Re: Problems disabling DMA
Zitat:
I think there may be some mis-communication going on here, so I want to reply to this message again.

Did you read the answers you received? Even Kano took his time to answer twice to your request - did you try to understand his answers?
Zitat:
nodma cheat in live mode disables DMA on the fly, but for HD install you have to use kernel cheats.

Zitat:
For older hardware we have a quite extensive boot menu at the live CD, which enables you to run and install Kanotix on such.

What was unclear here?
Greetings,
Chris
pcalvert - 07.09.2006, 01:13 Uhr
Titel: Re: RE: Re: Problems disabling DMA
slam hat folgendes geschrieben::
Zitat:
I think there may be some mis-communication going on here, so I want to reply to this message again.

Did you read the answers you received? Even Kano took his time to answer twice to your request - did you try to understand his answers?


Yes, I did. The answers were somewhat vague.

Zitat:
nodma cheat in live mode disables DMA on the fly, but for HD install you have to use kernel cheats.


Kernel cheats? Which one? I already mentioned "nodma" and "ide=nodma". Are those kernel cheats? Should one of those work? If not, then what does work?

slam hat folgendes geschrieben::
Zitat:
For older hardware we have a quite extensive boot menu at the live CD, which enables you to run and install Kanotix on such.

What was unclear here?
Greetings,
Chris


There is nothing unclear there. But how is that relevant? Kano just said that the cheats for the live CD don't apply to Kanotix installed on a HDD.

Phil
pcalvert - 07.09.2006, 01:29 Uhr
Titel: Re: Problems disabling DMA
pcalvert hat folgendes geschrieben::
I have an old laptop that requires that ACPI and DMA (mainly DMA) be disabled. The problem is that Kanotix (2005-04) seems to insist on enabling DMA even after I have told it not to use DMA.


Although it is not directly relevant to my main questions, I want to clarify this because what I said is technically not correct. My laptop should support ACPI, but since APM works fine I don't see the need to have it enabled. I also read a report that enabling ACPI on some old laptops may cause hardware damage. Since APM works fine I see no need to take the risk. I am not sure about DMA, though. DMA seems to work okay under Windows 2000 Professional. It is only under Linux that there is a problem. I don't know why. I figure that the best approach is to disable DMA and worry about fixing that problem later (if that's possible).

Phil
SteveR - 07.09.2006, 03:14 Uhr
Titel: RE: Re: Problems disabling DMA
Quite grateful for the Kanotix system. Thanks! Just a couple of findings with my own equipment that may be of interest because of the discussion above:

Desktop: ASUS P4P800-E Deluxe mobo and 2.4Ghz P4: Requires nodma in live CD and HD install. Runs reliably w/DMA in Windows. Don't know why DMA is a problem in Linux mode. Nevertheless, on Kanotix 2005-04 the nodma cheatcode was successfully implemented in HD install by simply adding the nodma cheatcode in the appropriate menu.list lines. In Kanotix this board runs disk ops much faster w/out DMA, and does not freeze up as it did frequently w/DMA.

Laptop: IBM 600E 400 Mhz P2 needed noacpi-nodma on liveCD, but seems to run well without the nodma cheatcode for a couple weeks now after HD Install. As a side note, This "old" laptop runs faster in Kanotix 2005-04 than it did on Win98SE for which it was designed. It runs full KDE desktop. It has 400 meg ram, and a low head seek time, high-rpm 40 gig HD. It is plenty fast enough for enjoyable use and normal work with Kanotix. I'm using it to write this. While sound and apm were difficult to work out initially, both were accomplished with some study, and I understand the machine better as well as Kanotix and Linux as a result.

Thanks again.

--Steve
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