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kwhiskers
28th December 2006, 04:17 AM
1. I noticed that my motherboard's bios has a setting called PCI Bus Master. I don't have a clue whether to enable or disable it, but it is presently disabled. I read that it has something to do with selecting either pio modes, allegedly slower, or dma, allegedly faster, for discs.

How do I want to set it under Linux (I have Windows, but only boot it to load the updates; I never use it).

2. While on the topic of bios, what is the proper way to set lba for linux use? I have my drives set in the bios to auto, which enables lba by default. Everything works fine, but I am wondering whether this is really the proper setting. When I install fedora, I always DON'T click the lba mode in the setup, so there is a conflict here, then, since it is enabled in bios, but fedora has it set to off. Is this fine?

3. A final bios question: I have read that for Linux one should not set the "enable pnp os" support. What is this and what is the proper setting for linux?

A curious thing, however, is that with the new motherboard that I got about 6 months ago, the bios no longer has this setting, but the manual says that the motherboard does indeed support pnp. So how do I disable it when there is no way to do it in the bios setup? Do I have to disable it? Apparently it isn't presently, but I have a hunch about a small problem that this might be the cause.

Jongi
28th December 2006, 08:21 AM
On point 2, I have found that I manually set disc access mode to large (HDs are 80GB and 250GB) otherwise I get a grub 18 error.

parish
28th December 2006, 06:23 PM
3. A final bios question: I have read that for Linux one should not set the "enable pnp os" support. What is this and what is the proper setting for linux?
On an Asus M2N32-SLI motherboard with enable pnp os disabled, I was getting "IRQ # disabled, nobody cares" messages, after which either audio or USB or ide disk access would no longer function properly, depending on what IRQs I had enabled/disabled in the BIOS. All of these issues were resolved by setting enable pnp os to enabled in the bios. Don't ask how long and how many reboots this took to figure out! :mad:

Don't know if it's right, if it will work for any other motherboard, or if it will even work for you on the same motherboard, but it worked for me.

Daniel

leigh123linux
28th December 2006, 06:39 PM
On an Asus M2N32-SLI motherboard with enable pnp os disabled, I was getting "IRQ # disabled, nobody cares" messages, after which either audio or USB or ide disk access would no longer function properly, depending on what IRQs I had enabled/disabled in the BIOS. All of these issues were resolved by setting enable pnp os to enabled in the bios. Don't ask how long and how many reboots this took to figure out! :mad:

Don't know if it's right, if it will work for any other motherboard, or if it will even work for you on the same motherboard, but it worked for me.

Daniel

Good point!

I run with it enabled without problem but notice "IRQ # disabled, nobody cares" messages .
But I will now disable as the linux 2.6 kernel does not require this to work. :D
However windows users will need to keep this function enabled. :p

kwhiskers
28th December 2006, 08:40 PM
OK, to summarize, then (keeping the same point order as the original question):

1. PCI Bus Master - still no ideas! Does Linux support this? Please explain with respect to Linux, somebody, and tell the proper settings (on/off).

2. LBA should be on, I guess, for Linux, when using modern hard drives. Mine are 300GB and 200GB respectively. Is this correct? So, how do I enable LBA in Fedora when I didn't do so at initial install?

3. For dual-booting Linux and Windows, it is best to have PnP OS on, so that Windows will work and Linux doesn't care.

rasker
9th November 2007, 05:48 PM
1) Sure it does. The drivers and the pci card will also have to support this. It doesn't matter much if everything is working. Busmastering is useful for cards that transfer large quantities of data (sata cards, video cards etc).

2) LBA is a way to get around an early bios disk size limitation (if I remember correctly). LBA and Large effectively do the same thing (again if I remember correctly) but do it in different ways. However if you format your drive and it was setup as LBA (or auto) it will probably not work if you change it to Large. You don't need to enable it in linux just in the bios. The bios will then show linux the disk a certain way and linux will use it that way. One annoying problem that arises when you fool around with this setting is that if you cmos ever gets reset then suddenly you can't boot (which is fixed by setting it back to what you had before). Best to leave it at the default setting for your bios.

3) yup. pnp allows windows (and linux actually, I think) to move the irq's around as it pleases to fix potential conflicts. With pnp set to off the OS will use Irq's and other settings set by the bios. So pnp=on the bios only initialises the hardware required to start the OS and the OS (whatever it is ha to initialise the rest) and pnp=off tells the bios to initialise all the harware on it's isa and pci bus (not sure if it applies to usb).

PabloTwo
9th November 2007, 06:19 PM
rasker has it right. (1) and (2) are really only functions at the bios level that effect the type of hardware you're using and it doens't really matter which OS you're running. (3) is OS dependent, but all modern OS's basically are 'pnp', including linux and should just be left to 'yes' in bios setting. Now, if you were going to install DOS 6.2 as your sole OS, then set pnp to 'no'.

Paul