Not logged in
Log in now
Create an account
Subscribe to LWN
An unexpected perf feature
LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
PostgreSQL 9.3 beta: Federated databases and more
LWN.net Weekly Edition for May 9, 2013
It always struck me as very odd that X, being an app (a special app, but still an app) had to muck around with hardware registers, and could even bring the system down when thing went wrong.
This seems a much nicer design, with the kernel concerned with the hardware and the X concerned with drawing stuff on the screen.
Back to the kernel
Posted Apr 28, 2009 16:37 UTC (Tue) by mikov (subscriber, #33179)
I am not saying that it doesn't in this case, but it is not as clear cut as people seem to thing. For one, drawing sometimes requires talking directly to the hardware. Not every graphics chip has a DMA command queue in system RAM, and even even for the ones that do, it is not always the best solution.
The command queue could be a FIFO in the chip. So, in some cases X has to talk to the hardware in order to draw. If we insist the kernel to be the only one touching the hardware, we have to make a kernel mode transition for every drawing command, which is not ideal.
Copyright © 2013, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds