[linux-elitists] What do you want in your kernel today?

Don Marti dmarti@zgp.org
Mon Apr 16 11:54:57 PDT 2001


An interesting forward from the linux-thinkpad list follows. First,
housekeeping. I have transplanted the drives and SCSI card from
the box that formerly hosted this list to a new box. It's still
capsicum.zgp.org, and nothing should have changed from your point of
view at all. The new box is from ASL, and has a VIA chipset with a _fan_
on the VT8363A system controller chip.  (AMD CPU, naturally.
ASUS A7V133 motherboard.)

I'm writing this while in voicemail for Prentice Hall. If you ever need
to get to their publicity people, just call 201-236-6541, a number which
does not seem to appear on their web site anywhere. (The site is one of
those laid-out-according-to-the-corporate-power-structure mazes that
makes you expect a piece of cheese if you ever find anything. And when
you call their main number, you get "For other departments, press 5.
<pause> For Communications, press 6." Tricky, tricky, tricky.) Damn,
I'm just trying to get a photo of one of their books to send to 100,000
people, is that so offensive?

I've escaped, but damn, nobody has read this, have they?
http://useit.com/alertbox/20010401.html Maybe I'll only review O'Reilly
books from now on.

Anyone want to sell me a slightly obsolete Slot A motherboard? Turned
out the former capsicum crashed when I used the keyboard, not other
times, which implies swapping out the motherboard will fix it.

Finally, here's a little item about laptops, IBM, DRM, DVDs, and one of
those little vacations to Hell we call a binary-only kernel module...



----- Forwarded message from Keith Frechette <kfrechet@us.ibm.com> -----

Date: Mon, 16 Apr 2001 14:11:28 -0400
From: "Keith Frechette" <kfrechet@us.ibm.com>
Subject: [ltp] FYI -- New ThinkPad T22 model for Linux includes DVD movie playback
To: linux-thinkpad@www.bm-soft.com
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This is an FYI, since I'm not aware that anybody noticed our success in 
rolling out "legal" Linux DVD movie playback with our ThinkPad models.

The IBM ThinkPad T22 laptop computer was released in early April 2001. For 
the Linux model, we were finally able to incorporate legitimate DVD movie 
playback, using an application called LinDVD, created by InterVideo, Inc. 
I had been working with InterVideo since last April (when they first 
publicly announced their intent to deliver DVD movie support on Linux), 
and all the pieces finally came together.  I've included some anecdotal 
information below for your information / amusement.

To implement legal Linux DVD movie playback support on a ThinkPad laptop 
that includes an "S-Video out" port, we had to overcome some very 
*interesting* hurdles. (While I can say "interesting" now, several months 
ago I would have chosen a different word. :-)) The obvious requirement 
that we had was to take adequate measures to protect the copyrights 
associated with DVD movie titles. For example, enabling the user to 
transfer DVD movies to other media (video tape, for example) via the 
S-Video port would likely have triggered a flood of lawsuits. (Although 
there may have been some happy Linux users!)

The primary hurdles were: 1) no standardized way for implementing 
Macrovision (copy protection) on Linux, and 2) open-sourced X servers 
could easily be hacked to disabled the necessary copy protection.

1) For laptops, the primary mechanism for stopping DVD movie piracy over 
the S-Video port is to encode the out-going video signal using 
Macrovision. Under Windows, the video driver architecture provides a 
standard mechanism that allows DVD playback apps to tell the video driver 
to enable Macrovision encoding when playing a protected DVD title. Under 
Linux, no such standard exists. Fortunately, IBM, S3, and InterVideo were 
able to come up with an interface that allows the LinDVD app to 
communicate with S3's driver for controlling Macrovision. Perhaps in the 
future the Linux community will define a standard interface for this, 
possibly taking advantage of some of the work we did.

2) Under Windows, the natural place to put the actual Macrovision control 
logic is in the video driver. Under Linux, however, video drivers (X 
servers) are generally open-sourced, so handling Macrovision control logic 
in the video driver is not appropriate. Instead, the code is placed in a 
separate, binary-only, kernel driver. While this provides adequate 
protection, it does tie the Macrovision support to specific kernels. 
Hopefully we can resolve that in the future by packaging the Macrovision 
control logic into a user-mode driver (e.g. a daemon running as root, 
which has access to I/O space).

In short, releasing DVD movie playback for Linux was not as simple as it 
initially seemed. However, with the constant cooperation of all the 
parties involved, we were able to work through the issues. It excites me 
when diverse teams work cooperatively together toward the common goal of 
improving the end-user experience. And I suppose that's what has drawn me 
to Linux.

So, we did it! I hope that our success helps to raise the bar just a 
little, that in the future DVD movie support on Linux will be commonplace, 
and that we can say to Windows users, "DVD movie playback -- yeah, we've 
got that."

-- Keith

Keith Frechette
Linux Development Lead, Mobile Computing Options and Software Development
IBM Research Triangle Park, North Carolina
kfrechet@us.ibm.com / 919-543-3761 / TieLine:441-3761
----- End forwarded message -----

-- 
Don Marti              "I've never sent or received a GIF in my life." 
dmarti@zgp.org            -- Bruce Schneier, Secrets and Lies, p. 246.
http://zgp.org/~dmarti/        (Free the Web: http://burnallgifs.org/)



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