svn commit: r222356 - projects/pseries/kern

[Nathan Whitehorn]

On 05/27/11 11:02, John Baldwin wrote:
> On Friday, May 27, 2011 10:27:28 am Nathan Whitehorn wrote:
>> Author: nwhitehorn
>> Date: Fri May 27 14:27:28 2011
>> New Revision: 222356
>> URL: http://svn.freebsd.org/changeset/base/222356
>>
>> Log:
>>    On multi-core, multi-threaded PPC systems, it is important that the threads
>>    be brought up in the order they are enumerated in the device tree (in
>>    particular, that thread 0 on each core be brought up first). The SLIST
>>    through which we loop to start the CPUs has all of its entries added with
>>    SLIST_INSERT_HEAD(), which means it is in reverse order of enumeration
>>    and so AP startup would always fail in such situation (causing a machine
>>    check or RTAS failure).
>>
>>    The best fix is probably to change this from a LIST to a TAILQ, but fix
>>    this by looping through to add new cpus to the end of the list.
> Just make it a STAILQ.  That has a STAILQ_INSERT_TAIL() method and doesn't
> change the ABI of 'struct pcpu'.  It just adds an extra pointer to the head.

I did that, and it works well. A patch against HEAD can be found at
http://people.freebsd.org/~nwhitehorn/pcpu_tailq.diff. Let me know if it 
looks OK (or if there are any objections to committing it).
-Nathan