Messages in this thread | | | Date | Mon, 31 Dec 2007 12:21:12 -0600 | From | Robert Hancock <> | Subject | Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override |
| |
Alan Cox wrote: >> "You plug in PCI DEBUG card and it overclocks your machine" is bad >> scenario.. (I don't know if it does... can PCI card emulate ISA timings?) > > Easily. Its a bit more restricted by later spec revisions but it can halt > your box of a week or two if it wants. Video cards used to pull this > stunt for marketing benchmark numbers.
The drivers, specifically (the old "don't check if the command FIFO is full before writing, just write anyway and if it's full let the whole PCI bus stall while the FIFO empties out" trick).
I rather doubt any of those PCI POST debug cards would bother to accurately emulate the ISA timings of normal port 0x80 accesses, however. Most likely if you plug those in, port 0x80 accesses suddenly become lots faster now that the writes are completing on the PCI bus before ever hitting ISA/LPC..
-- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/
| |