Ubuntu install issue, I can haz help pls? kthxbai

[Occulus]

Yesterday I downloaded and burned a shiny new Ubuntu CD (Ubuntu 8.10 desktop AMD 64-bit edition). Actually, I went further than putting it on a CD; I followed the instructions on this page for putting Ubuntu (or most other distros) onto a USB stick to install from that (I have reasons for doing this). Actually, it's not merely a stick I'm using- I rigged my little 2GB mp3 player to act like a removable drive, but that's neither here nor there.

I tried to install it from both the CD and the USB stick, and the install won't move past the splash screen following the install menu. Instead, I get an error complaining that

Aperture beyond 4GB. Ignoring.
Your BIOS doesn't leave a aperture memory hole.
Please enable the IOMMU option in the BIOS setup.
This costs you 64MB of ram.

Following this, I get dumped to a prompt that apparently is capable of getting me nowhere.

Diligent Googling revealed that I am in no way the only one experiencing this issue. It seems that Ubuntu doesn't know about PCI-e motherboards which completely lack an AGP port. The installer is trying to allocate 64Mb of RAM for an AGP board, even in cases where this is not possible. Compounding the issue, my motherboard has no option to enable IOMMU, which is apparently AGP-related. There is no mention of the AGP aperture memory hole in my BIOS either.

The problem came up in multiple Google search results for "ubuntu IOMMU" and "ubuntu aperture memory hole", and after reading a few of the result pages, it seems the problem is confined to those of us who have systems new enough to have dumped AGP capability entirely and who have 4GB or more of system RAM. Suggestions such as adding as an install option iommu=noagp, iommu=soft, iommu=memaper=3 pci=nommconf, iommu=yourmom, etc., have either had no effect or (for others but not me, yet) caused a kernel panic. The type of motherboard/CPU/PCI-e video board(s) does not seem to make a difference so long as the two conditions are met.

This seems to me to be a rather gigantic bug in the Ubuntu installer. It makes no sense to me that this wouldn't have been caught and fixed before the distro was put up for download, so... what gives? Does anyone here know what I should do? Replacing the motherboard and/or cutting down on RAM to make the error irrelevant is not an option for me, since this machine is also my primary computer.

Any ideas at all would be appreciated!

[RoyGBiv]

1. It's not in the installer ...

... specifically.

It seems to be in the kernel, not that this helps you.

I skimmed a couple of the major bug-report threads, and I don't think this is going to be solved with a few commands passed to the kernel on boot, but there was one mentioned you didn't that you might at least try:

acpi=noirq

I didn't see mention of this anywhere, but what I'm inclined to suggest involves one of two things:

1) Install the 32 bit version and see if there's a difference. There's not a huge advantage to using 64-bit anyway unless you run specialized software intended to take advantage of it. All the chatter I saw was about the 64 bit version.

2) Install 8.04 LTS, which has an older kernel.

[Occulus]

2. I asked over at Penny Arcade in Moe's Stupid Technology Tavern

and got this in response.

So, I guess I'm supposed to disable my NV cards, enable the onboard GPU, try to install Ubuntu, perhaps pass iommu=noaperture to the installer, or use the 32-bit build.

If what Barrakketh said about AMD CPU's is true (no reason to doubt that), then using the onboard GPU to install Ubuntu may work. I might even find the IOMMU option I'm looking for once I do so.

Humorous aside: my BIOS overclocking menu item label? JustWooT. Not a joke.

[pokerfan]

3. One of the reasons I installed the 32 bit version

despite having a brand new quad core machine is that my research suggested that the 64 bit version just isn't quite ready for prime time. Given that this was my first serious foray into the world of linux, I didn't want to be struggling with 64/32 bit issues at the same time I was on a linux learning curve.

[RoyGBiv]

4. Yeah ...

It's really not all it's cracked up to be either, unless you do use that specialized software.

I ran some tests with various things between my 64/32 installations. My performance improvement with apps that were set up to take advantage of it was in the single percentage point range. Most things were less than 1%, and some actually performed worse.