[LinuxBIOS] PATCH: lx car that returns from disable_car

Marc Jones marc.jones at amd.com
Tue Jan 8 00:57:15 CET 2008

ron minnich wrote:
> 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 :-(
> ron

The hlt is really the right thing to do and I would rather it be in 
there. Correctly behaving jtag should be able to handle it. I understand 
clearing the fifo so do it before the hlt.


Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones at amd.com

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