Bug 2118 - via: Invalid DMA header command.
Summary: via: Invalid DMA header command.
Status: RESOLVED FIXED
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/other (show other bugs)
Version: DRI git
Hardware: x86 (IA32) Linux (All)
: high normal
Assignee: Default DRI bug account
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Reported: 2004-12-20 12:00 UTC by Thomas Hellström
Modified: 2005-11-23 10:19 UTC (History)
0 users

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Description Thomas Hellström 2004-12-20 12:00:19 UTC 
For some applications, The following message from the VIA command verifier appears:

*ERROR* Invalid / Unimplemented DMA HEADER command. 0x0

Which suggests either a bug in the verifier or in the Mesa driver. 
I'm entering this for reference and will try to track it down as soon as possible. 

/Thomas
Comment 1 Thomas Hellström 2004-12-20 15:05:44 UTC 
This is caused by the verifier exiting to state_command after a single
HC_COMMAND_FIRE, followed by a 0x00 command. 

Seems like a HC_HEADER2 should be inserted inbetween. 

The command regulator actually accepts this, whereas the PCI path 
(taken from the original via dri driver) does not, and hangs the machine.
I suggest fixing up the Mesa driver not to issue this command sequence.

/Thomas
Comment 2 Thomas Hellström 2004-12-21 09:24:44 UTC 
OK, previous message was a probably not correct. Apparently the command verifier
exits the state due to vertex data that is misinterpreted as a fire command. 

In the worst case this means that the command verifier needs to interprete and
count all the vertex data :(. I'm not modifying anything at the moment, since
both the command verifier and the PCI paths might need additions. This bug will
show itself as misrendering in a couple of applications.

Anybody with a detailed understanding of how the command regulator exits the
vertex data state?

/Thomas
Comment 3 Thomas Hellström 2005-11-24 05:19:51 UTC 
Fixed some time ago.

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