amd64/138882: Can't install FreeBSD 7.2
avg at freebsd.org
Fri Sep 18 16:06:01 UTC 2009
on 18/09/2009 17:20 Andriy Gapon said the following:
> I am debugging a somewhat related problem with head code and SB700 ohci.
> The problem is that certain ports become unusable of there is a keyboard or mouse
> attached to them during boot.
> My findings so far:
> 1) the problem happens only with ports provided by ohci0 (the very first PCI OHCI
> 2) the problem is that some configuration registers of ohci controller get
> mysteriously changed after ohci driver configures them and before the first
> interrupt gets generated by the controller; registers in question are
> HcControlHeadED and HcDoneHead.
> Looks like perhaps either the controller doesn't get "sufficiently"
> reset/re-initialized or firmware/SMM code touches the controller after handover
> procedure completes.
My current suspicion is that ohci(4) doesn't clear some memory that it allocates
for shared use with HC (hardware) and sets a HC register to point to that memory.
So when HC goes to operation state and examines that memory and sees something
that looks like valid data, HC uses it and goes bad way.
But this is just a hypothesis that I've just dreamed up.
I am going to test it some time later.
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