[LinuxBIOS] PATCH: lx car that returns from disable_car

ron minnich rminnich at gmail.com
Tue Jan 8 00:46:54 CET 2008

On Jan 7, 2008 2:18 PM, Marc Jones <marc.jones at amd.com> wrote:

> I don't like taking the hlt() out of die(). Can you describe when you
> where having issues?

In the early days of LinuxBIOS, using an American Arium JTAG debugger,
I found that I could not examine memory or, in fact, do much of
anything on JTAG once the CPU halts. It's a real hassle to get to a
hlt() and know that the info you need is in memory, and you can't get
to it.

I'd really prefer not to have a hlt instruction in there, but if it is
a problem, I guess we can put it back.

As for the UART, similar issue: I had problems years ago where I had
to intuit what got sent to the UART because it did not make it out --
it could get stuck in the FIFO or other intermediate places at times.
I have found it handy to push a gazillion NULLS out to make sure I see
all that is there (Actually, this is a decades old OS hacking trick
... dating back to, well, I'm embarrassed to say it).

> It could be coherency issues in CAR with die(). In
> FS2 check your config and set Coherent to off. You need it on/auto in
> normal operation.

It's not just an FS2 issue. I don't even have one any more -- it seems
to have gotten lost in the move :-(


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