FreeBSD doesn't boot anymore on RPi

[Michael Tuexen]

On 17 Jun 2014, at 06:44, Jia-Shiun Li <jiashiun at gmail.com> wrote:

> On Mon, Jun 16, 2014 at 1:53 PM, Michael Tuexen <tuexen at freebsd.org> wrote:
>> On 16 Jun 2014, at 03:04, Andreas Schwarz <freebsd.asc at strcmp.org> wrote:
>>> On 21.05.14, Michael Tuexen wrote:
>>> 
>>> Hi all,
>>> 
>>>> I just built r266500 and when booting that on a Raspberry Pi the booting stalls
>>>> after displaying Kernel args: (null).
>>> 
>>> I run still in this problem, the last kernel which was working for me is r265403. Is this
>>> a know problem?
>> Yes, it is known. There were two problems, one is fixed now. The other problem
>> is currently been worked on. Right now, you need to revert r266083 and should
>> get a working kernel. If not, please let us know.
>> 
> 
> adding ian@ and markm at .
> 
> 
> Hi,
> 
> looks ARM1176, aka RPi, has different register location for
> performance counters.
> 
> r266083 uses PMC registers defined at c9:c12~c14 of CP15. The location
> is true for Cortex-A8[1] onward. For ARM11 which predated A8, however,
> these registers are located at c15:c12[2]. c9:c12~c14 are undefined on
> ARM1176.
> 
> According to ARMARM, pre-ARM11 cores do not have PMC. So they must
> have decided the debut location of PMC was not suitable anymore , and
> moved to c9 afterward.
> 
> For RPi I think it is simpler to exclude ARM11 in original code for
> now. After making sure PMC registers on ARM11, despite different
> location, are still suitable for the purpose, it can have dedicated
> handling different from other cores.
> 
> Other cores like pj4b and Krait may need additional check.
> 
> [1] Ch.3.2.1 of Cortex-A8 TRM r3p2,
> http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0344k/ch03s02s01.html
> [2] Ch.3.2.1 of ARM1176jz-s TRM r0p7,
> http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0333h/ch03s02s01.html
Please have a look at the thread 'Re: svn commit: r266083 - in head/sys/arm: arm include'
on current at freebsd.org. The patches being discussed there allow the RPI. Basically
they use different registers on different platforms as you write.

Best regards
Michael
> 
> -Jia-Shiun.
>