Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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 [email protected]
Home Page: http://www.roberthancock.com/

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux