[LinuxBIOS] patch for making system run past disable_car

ron minnich rminnich at gmail.com
Thu Dec 13 01:58:03 CET 2007

On Dec 12, 2007 4:50 PM, Carl-Daniel Hailfinger
<c-d.hailfinger.devel.2006 at gmx.net> wrote:

> I don't like this. disable_car() should just be able to return without
> problems. If it can't do that, fix it.

I've never found the fix. What if it is a hardware limitation on LX?
Note that on several LX platforms on V2, we have this:

And it's because  I could never get it to work any other way. CAR is
very tricky sometimes. Just take a deep look at the opteron code --
you'll see that we do some things that make CAR fail on most systems,
due to a known limitation in the K8.

> Otherwise we have to document the call to stage1_end() as a requirement
> of any diable_car() function and *justify* it.

only those architectures that we can't get it to work on.

> Why exactly do we invalidate the stack? If the stack is clobbered, the
> contents of variables should be in a clobbered state as well. In that
> case, I suspect parts of our v3 code would misbehave as well.

no, because what happens here is you are essentially dropping all
local variables etc. -- this is a jump to a new context, and all the
variables in that context are re-initialized.

Anyway, maybe Marc can tell us what is wrong. I just don't know. I
never solved it on the LX either. I'm happy to see it solved but, at
the same time, I don't want to burn my next month of limited cycles on
something i have a workaround for.


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