Via82cxx chipset problem

Via82cxx chipset problem

[Cheryl Homiak]

I tried this question on another list and was told not to try to change my
mhz speed because I would corrupt my hard drive possibly. But does this
mean I am actually running at only 33mhz.? This doesn't seem like a viable
way to run my computer and I am having problems with installing new memory
that may be related to this. My original message is below; any help would
be appreciated.
Thanks.

try here first.
I have a via82c597 rev 4 chipset and an Award bios. I have anabled the
via82cxxx support in my kernel, but perhaps I do not understand what
numbers to put in on the command line, or for which ide to put them in,
because no matter what I do a 33mhz bus speed is assumed; if I try putting
66 even in I get something about this being impossible.
I have included part of my dmesg here, and have included enough so you can
see my setup and a couple of other messages that puzzle me.
Any help would be appreciated.

PCI: PCI BIOS revision 2.10 entry at 0xfb360, last bus=2
PCI: Using configuration type 1
PCI: Probing PCI hardware
PCI: 00:07.3: class 604 doesn't match header type 00. Ignoring class.
Unknown bridge resource 1: assuming transparent
Unknown bridge resource 2: assuming transparent
PCI: Using IRQ router VIA [1106/0586] at 00:07.0
Activating ISA DMA hang workarounds.
Uniform Multi-Platform E-IDE driver Revision: 6.31
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
VP_IDE: IDE controller on PCI bus 00 dev 39
VP_IDE: chipset revision 6
VP_IDE: not 100% native mode: will probe irqs later
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
VP_IDE: VIA vt82c586b (rev 47) IDE UDMA33 controller on pci00:07.1
    ide0: BM-DMA at 0xe400-0xe407, BIOS settings: hda:DMA, hdb:DMA
    ide1: BM-DMA at 0xe408-0xe40f, BIOS settings: hdc:DMA, hdd:DMA
hda: ST32520A, ATA DISK drive
hdc: ATAPI CDROM, ATAPI CD/DVD-ROM drive
hdd: Conner Peripherals 420MB - CFS420A, ATA DISK drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15
hda: 4927104 sectors (2523 MB), CHS=4888/16/63, UDMA(33)
hdd: 832608 sectors (426 MB) w/64KiB Cache, CHS=826/16/63, DMA
hdc: ATAPI 24X CD-ROM drive, 120kB Cache, DMA
Uniform CD-ROM driver Revision: 3.12

Re: Via82cxx chipset problem

[Lionel Bouton]

Cheryl Homiak wrote:

> I tried this question on another list and was told not to try to change my
> mhz speed because I would corrupt my hard drive possibly. But does this
> mean I am actually running at only 33mhz.?


Your PCI bus is most probably running at 33 Mhz. As it is intended to 
run at this speed. There's nothing wrong with that. The :
"ide: Assuming 33MHz system bus speed for PIO modes; override with 
idebus=xx"
message is a warning that the PCI bus speed cannot be reliably detected.

For IDE PIO transfer modes the PCI bus speed is a reference which is 
used by timers which regulate IO transfers. As some computers run the 
PCI bus at other frequencies, mainly 25 and 30 MHz instead of 33 MHz 
(for example: old ones with Pentium 75 (25MHz), 90, 120, 150 (30MHz)), 
the idebus parameter is there to allow the timings to be fine-tuned for 
these machines. Nothing to worry about.

-- 
Lionel Bouton

-
"I wanted to be free. I opensourced my whole DNA code" Gyver, 1999.

Re: Via82cxx chipset problem

[Tim Moore]

Cheryl Homiak wrote:
> 
> I tried this question on another list and was told not to try to change my
> mhz speed because I would corrupt my hard drive possibly. But does this
> mean I am actually running at only 33mhz.? This doesn't seem like a viable
> way to run my computer and I am having problems with installing new memory
> that may be related to this. My original message is below; any help would
> be appreciated.
> Thanks.

Most modern motherboards use a 1/2, 1/3 or 1/4 divider on the memory bus
(set in BIOS) to get PCI values.  idebus= is used for anything other
than 33MHz:

Mem	PCI	divider	idebus=
66	33	1/2	default
75	37.5	1/2	38
85	42.5	1/2	43
100	33	1/3	default
133	33	1/4	default

For example, setting the bus at 75MHz would mean 'idebus=38' on the boot
command line or in lilo to prevent timing problems which could lead to
disk data corruption.  Most PCI bus related data corruption occured when
driving the bus more than 15% over spec.

rgds,
tim.
--

Re: Via82cxx chipset problem

[Daniel R. Warner]

Cheryl Homiak wrote:

> I tried this question on another list and was told not to try to change my
> mhz speed because I would corrupt my hard drive possibly. But does this
> mean I am actually running at only 33mhz.? This doesn't seem like a viable
> way to run my computer and I am having problems with installing new memory
> that may be related to this. My original message is below; any help would
> be appreciated.
> Thanks.


The PCI bus runs at 33mhz on modern motherboards. Only motherboards made 
to provide "odd" FSB timings (such at 75, 83 mhz) need change this. 
Although your FSB (also known as memory bus) runs at 100, 133 or faster, 
the PCI bus is still running at 33mhz.
The short?
Don't worry about that warning, it's not really a warning :)
-D