KMS Color Tiling - not enabled by default?

[chrisr]

My original Xorg.0.log file was showing the following:

(II) [KMS] Kernel modesetting enabled.
(WW) VGA arbiter: cannot open kernel arbiter, no multi-card support
(**) RADEON(0): Depth 24, (--) framebuffer bpp 32
(II) RADEON(0): Pixel depth = 24 bits stored in 4 bytes (32 bpp pixmaps)
(==) RADEON(0): Default visual is TrueColor
(**) RADEON(0): Option "EnablePageFlip" "on"
(**) RADEON(0): Option "AccelDFS" "on"
(**) RADEON(0): Option "RenderAccel" "on"
(**) RADEON(0): Option "AccelMethod" "EXA"
(==) RADEON(0): RGB weight 888
(II) RADEON(0): Using 8 bits per RGB (8 bit DAC)
(--) RADEON(0): Chipset: "ATI Radeon 9600 AS (AGP)" (ChipID = 0x4153)
(II) RADEON(0): AGP card detected
(II) RADEON(0): KMS Color Tiling: disabled

This surprised me because the man page suggested that it was on by default. So I added a line to my xorg.conf file, and now it says:

(**) RADEON(0): Depth 24, (--) framebuffer bpp 32
(II) RADEON(0): Pixel depth = 24 bits stored in 4 bytes (32 bpp pixmaps)
(==) RADEON(0): Default visual is TrueColor
(**) RADEON(0): Option "EnablePageFlip" "on"
(**) RADEON(0): Option "AccelDFS" "on"
(**) RADEON(0): Option "ColorTiling" "on"
(**) RADEON(0): Option "RenderAccel" "on"
(**) RADEON(0): Option "AccelMethod" "EXA"
(==) RADEON(0): RGB weight 888
(II) RADEON(0): Using 8 bits per RGB (8 bit DAC)
(--) RADEON(0): Chipset: "ATI Radeon 9600 AS (AGP)" (ChipID = 0x4153)
(II) RADEON(0): AGP card detected
(II) RADEON(0): KMS Color Tiling: enabled

So is this a Good Thing? Or was Color Tiling disabled for a reason?

[agd5f]

It's not enabled by default with kms at the moment. It is enabled by default with non-kms.

[chrisr]

Because...?

It's not enabled by default with kms at the moment.

Does it not work properly with KMS yet? I did experience a complete PC freeze last night, which would imply something kernel-related. (I am running 2.6.31.6.) However, I couldn't find a single diagnostic message to indicate what the root cause was so it would be unfair to pin the blame on KMS/Color Tiling just yet...

[agd5f]

It shouldn't be any more or less stable than kms in general, but as we move to kms, one thing at a time.

[chrisr]

ColorTiling with KMS on 2.6.31.6

It shouldn't be any more or less stable than kms in general, but as we move to kms, one thing at a time.

Interestingly, the random complete kernel freezes I experienced two or three times while I happened to have ColorTiling and KMS enabled on 2.6.31.6/F12 haven't happened since I disabled ColorTiling again.

I wonder if there's a connection? ;-)