Re: Activating L2 cache on a Crescendo G4 400 card (powerMac 7300)
On 28 Dec, this message from Philippe TEISSIER echoed through cyberspace:
>> On 27 Dec, this message from simonraven@istop.com echoed through cyberspace:
>>> too bad there isn't a kernel driver to enable the cache on those cards
>>> at boot up under debian, cuz then you wouldn't need bootx, you'd be
>>> able to quik ;).
>>
>> There is, actually. You can specify an l2cr value on the kernel command
>> line. Here is mine on my G3-upgraded 7600:
>>
>> mlan@piglet:~$ cat /proc/cmdline
>> root=/dev/sda4 console=ttyS0 l2cr=0xa9000000 console=tty0 video=scrollback:64k
>> video=controlfb: video=matrox:
>> ^^^^^^^^^^^^^^^
> What is the kernel you use ? a patched one or an official release ?
BenH, but that shouldn't make any difference.
> I just DL the last stable sources. Where can I find a command line
> parameters description ?
Nowhere I know of.. there maybe a file under Documentation/ describing
some of them, but most probably not all.
> For example, the video parameters ... One is for a matrox millenium card, I
> think, but the 2 others ?
The first one is supposed to use 64k as a scrollback buffer; you can use
more or less memory here depending on how far back you want to scroll on
the console with shift+pgup/pgdwn
The second and third options, through their order, specifiy the order of
the internal and Matrox framebuffers: control will be fb0, and matrox
will be fb1. If any of those needed options, they would be specified
there... but I use none.
>> You can also have a look at this page for more info (it's a bit outdated
>> by mostly still relevant):
>> http://www.cpu.lu/~mlan/linux/dev/g3upgrade.html
> I had a look there, and they seems to say that the last 2.4.xxx kernels
> include this patch, so it should be OK. I'll test that soon. I would like to
> be able to quik :)
Yeah, when you don't use MacOS, it's a good solution once you get it
working. If you still use MacOS, it's a pain since MacOS will overwrite
the OpenFirmware config to boot quik; so you will have to reset that
everytime on shutdown in MacOS.
>> PS By the way, I suppose you're talking about L2 (level 2) cache, not
>> L3? And I also think it's worth a benchmark removing the old L2 cache
>> DIMM on the motherboard...
> Right, I don't know why I typed L3 instead of L2 ...
> Could you detail the last sentence "it's worth ...". Sorry for my english
> (I'm a french student still learning english ...) : Does that mean it's
> better for performance to remove the old cache ? And if yes, why ?
Well, the documentation for my G3 card says to remove the on-board L2
cache DIMM. The reason is that it will be 'degraded' to an L3 cache, but
a slow and small cache. So, it _may_ hinder performance more than it
helps. Just try it...
The point to keep in mind is that in order to make the G3 upgrades work,
some _must_ remove the cache, some _must_not_ in order for the upgrade
to work.
I'd say: if your box works with the cache removed, than do it.
Cheers
Michel
-------------------------------------------------------------------------
Michel Lanners | " Read Philosophy. Study Art.
23, Rue Paul Henkes | Ask Questions. Make Mistakes.
L-1710 Luxembourg |
email mlan@cpu.lu |
http://www.cpu.lu/~mlan | Learn Always. "
Reply to: