[conspire] question on Biostar P4M890-M7 Based on the VIA P4M890+VT8237A chipsets

[Rick Moen]

Quoting K Sandoval (indigo.kai at gmail.com):

> Biostar P4M890-M7 Socket 775 Motherboard
          ^^^^^^^^^
              |
              --- motherboard's model designation

> Based on the VIA P4M890+VT8237A chipsets
                   ^^^^^^ ^^^^^^^
                     |       |
                     |       ------ southbridge chip
                     -------------- northbridge chip

A motherboard's northbridge chip never has particular importance for OS
support, per se, i.e., not counting the importance of the attached video
chip if any.  (At least, I've never heard of the northbridge having such
importance.)  It's the place where the CPU, RAM, video, and other
very-high-speed devices attach.  Basically, it's the CPU/RAM bus.  In
this case, it's a bus for Intel P4-class CPUs (Core 2 Duo, P4, Celeron),
and for DDR2 or DDR-400[0] SDRAM (max. = 4GB) at memory-bus speeds up to
533 MHz.  

The southbridge chip is where all the main I/O is, and in particular the
SATA or PATA, ethernet, USB, serial/IR/parallel, and (slow-ish, e.g.,
legacy PCI) expansion slots are.  It's thus of crucial importance for OS
drivers.

Here's a block diagram of a P4890 + VT8237A motherboard.  Notice that
the northbridge chip includes an integrated VIA UniChrome Pro[1] 2D/3D
video chip with built-in MPEG2 decoder, a PCI-E x16 attachment, and a
PCI-E x 1 (standard PCI-E) attachment -- both being distinct data paths
from the two legacy PCI slots hung off the VT8237A chip:
http://www.via.com.tw/en/products/chipsets/p4-series/p4m890/

At least a 400W ATX PSU is recommended.

This page claims Biostar's motherboard uses a VT8237R+, not a VT8237A:
http://www.pcstats.com/articleview.cfm?articleID=2055  In fact, so does
this page at Biostar's site:
http://www.biostar-usa.com/mbdetails.asp?model=P4M890-M7%20PCI-E
So, from this point foreward, I'll assume VT8237R+.


> http://www.viaarena.com/default.aspx?PageID=420&OSID=35&CatID=2830&SubCatID=169

That's VIA's proprietary 2D/3D video driver compiled and packaged for
some laughably small set of Linux distributions.

> http://www.viaarena.com/default.aspx?PageID=420&OSID=25&CatID=2580&SubCatID=101

That's the alleged source code -- actually, it's a cheesy dodge where
they put all the functionality into a proprietary, binary-only library
and surround it with a source-code wrapper and say "See?  We gave you
source code.  What are you complaining about?"[2]



> http://www.avalue.com.tw/products/ESM-CN700.cfm
> I am not sure if this page involves my chipset, I saw the VIA CN700 /
> VT8237R+ chipset, and I am interested in the  VT8237R+ chipset.

Well, yes and no.  (There's not just _one_ chipset.)  The southbridge
chipset is the same; the northbridge is one serving a completely
different class of CPUs, the VIA "Eden" series, which are very likely
related to the old C7 Ezra / Nehemiah / Esther "CentaurHauls" series of
very low-power CPUs.

> Can someone help me figure out if this motherboard / chipset is
> actually Linux compatible?

Now that I've laid some groundwork by explaining some of the jargon,
let's have at it.

Your problem areas are pretty much always:

o  video
o  SATA (or PATA, which is often called "EIDE" or such)
o  ethernet
o  sound
o  wireless (if any -- none on this motherboard)

Confirming my surmise about proprietary video drivers (footnote 2), I
see an "OpenChrome" project to develop/improve _real_ open source
drivers for the UniChrome Pro, mentioned here:
https://help.ubuntu.com/community/OpenChrome  As that page clarifies,
the actual X.org drive you would be using is called "via".  I'm guessing
there's no open source support (yet) for the UniChrome Pro series's 3D
functions.

Alternatively, you could of course buy a less troublesome video card
separately, and put it in the PCI-E x16 slot.  Or use the VESA driver,
and get not-as-good performance.

SATA: sata_via driver.

Ethernet uses a Realtek RTL8201CL PHY chip, according to Biostar's page.
However, I'm a bit unclear on what specific MAC in the Southbridge is
behind the PHY.  I'm betting it'll be one that requires the via_rhine
and i2c_viapro ethernet drivers.

Sound is Realtek ALC658, according to Biostar's page:  Driver is
something-or-other in ALSA, functioning properly, I gather, starting
with the ALSA drivers included in 2.6.11 and later.


> Am I trying to put the horse before the cart?  Or should I wait 4 or 5
> months and see if drivers become available?

Well, frankly, it seems like it _might_ be a minor exercise in
masochism, but everything can be supported in a current distro (i.e.,
one whose installer has a recent kernel and X.org driver set).  At
worst, you might need to fetch a proper X.org driver after installation
and/or futz around a lot with video config.

A couple of closing comments:  You'll notice that I had little to say
about your ubuntuforums link.  I did read it, but it didn't seem useful,
which is about par for the course.  One of the obstacles to finding
reliable Linux hardware-support information through Web searching is a
small ocean of mistaken or otherwise obstructive commentary on Web
forums.

The other thing is that one should almost always avoid Linux drivers
available separately from hardware manufacturers if humanly possible,
for a whole bunch of reasons, which maybe I could get into some other
time.



[0] There's a single memory controller channel, which is part of why
this motherboard's so cheap.  Naturally, this slightly reduces RAM
performance.

[1] Since "UniChrome Pro" is just a name from VIA's marketing
department, you might correctly guess that it isn't an exact designation
for the specific video chip in this motherboard, which is probably a VIA
model CN700 or VN800, though I cannot tell which it is from available
Web pages about the Biostar.

[2] To be honest, this one time, I _didn't_ go to the effort of
downloading the goddamned Zip archive and grovelling through it to
verify that there's a "secret sauce" binary core inside an allegedly
open source package.  So, technically, this is a guess on my part, based
primarily on the vibes I get from the Web pages' presentation, and from
from my experience with such things.  Certainly, I could be mistaken in
this case.  More here:
http://skeleton-danse.blogspot.com/2007/02/xorg-drivers-for-via-unichrome-pro.html
http://www.hombrepac.com.ar/software-libre/linux/how-to-via-k8m890-chrome-9-igp-and-linuxs-xorg-ubuntu-edgy-610/

Typically, companies like VIA use the aforementioned cheesy dodge to
hide their chip engineering, and keep Our Lords in Hollywood from
getting upset over your getting too-easy uncontrolled access to things
like high-quality video-in/out ports and the MPEG-2 decoder functions.