Re: PPro write combining

Alan Cox (
Mon, 27 Jan 1997 21:17:23 +0000 (GMT)

> I downloaded the source to 2.1.22 and found no reference to enabling write
> combining in the sources. I have the documentation on how to do it, a
> Pentium Pro machine with a PCI video card and the Intel IDE accelerator.

Your bios is supposed to have done this.

> enable, and then use IPI to synchronise it over all available processors).
> I might need some help with the x86 assembly language stuff (I don't use
> instructions like WMSR all that often :-), and the help of the linux-smp
> people will also be necessary.

Actually if you do it during the boot up before you go MP its not so bad.

> I had started upon a root-level source in C++, but found that doing this
> stuff live would probably freak out the OS, and the best way to do it is at
> hardware initialization time.

It might be interesting to try. I don't think it will freak the OS if you
do it as root at iopl(0)