Patches to allow usefdt mode that works on a 2 socket PowerMac3, 6 example too --and makes more work on 2-socket/1-core-each PowerMac11, 2
Mark Millard
marklmi at yahoo.com
Sat Apr 13 18:39:24 UTC 2019
[My adjustment to fdt_add_subnode_namelen was inept.]
On 2019-Apr-12, at 16:17, Mark Millard <marklmi at yahoo.com> wrote:
> On 2019-Apr-12, at 14:20, Dennis Clarke <dclarke a t blastwave.org> wrote:
>
>> On 4/12/19 4:51 PM, Mark Millard wrote:
>>> On 2019-Apr-12, at 13:13, Dennis Clarke <dclarke at blastwave.org> wrote:
>>>> On 4/12/19 3:19 PM, Mark Millard via freebsd-ppc wrote:
>> .
>> .
>> .
>>>>
>>>> Would you be so kind as to paste all this into :
>>>>
>>>> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=233863
>>>>
>>>> Really I would like to run some tests and follow up in the bug reports.
>>> Okay I'll paste them in as attachments. But be warned:
>>
>> Fair warning received loud and clear :-)
>>
>>> The 2 files do not deal with threads being stuck sleeping
>>> (and, so, the fans going) or other such. The stuck-sleeping
>>> problem happens for both multi-socket G5's and multi-socket
>>> G4's. (I do not have access to single-socket multi-core
>>> powerpc64 or powerpc machines to test.)
>>
>> I have multiple G5 type boxen and will try them out. At least try
>> to.
>>
>>> So do not expect too much from these patches: They address
>>> some necessary issues but are not sufficient for everything.
>>>
>>
>> Of course. No problem.
>>
>>
>>> These patches for the openfirmware->fdt translation are
>>> closer to being reasonable for FreeBSD official use
>>> than my highly context-specific stuck-sleeping patches for
>>> usefdt mode.
>>
>> Well to be frank we know this is for mac g5 hardware and thus having
>> them working at all in any fashion is better than the current situation.
>> Apple made a ton of them and they are dirt cheap and available as
>> opposed to the IBM Power situation which is expensive and just in
>> datacenters.
>
>
> I have added another attachment with patches for having hang-ups
> at AP startup happen less often. These are in AIM-specific code
> and so has less of a chance of causing other contexts problems.
> They are also powerpc64 specific. Again, the patches are
> investigatory and not in a form for direct check-in to FreeBSD.
>
> This pair of patches narrows the time period over which threads
> from the stages:
>
> SI_SUB_KTHREAD_INIT = 0xe000000, /* init process*/
> SI_SUB_KTHREAD_PAGE = 0xe400000, /* pageout daemon*/
> SI_SUB_KTHREAD_VM = 0xe800000, /* vm daemon*/
> SI_SUB_KTHREAD_BUF = 0xea00000, /* buffer daemon*/
> SI_SUB_KTHREAD_UPDATE = 0xec00000, /* update daemon*/
> SI_SUB_KTHREAD_IDLE = 0xee00000, /* idle procs*/
> #ifndef EARLY_AP_STARTUP
> SI_SUB_SMP = 0xf000000, /* start the APs*/
> #endif
>
> can conflict with starting an AP via an slb replacement position
> picked via expressions like mftb()%n_slbs . It does this by
> explicitly picking and setting up a slb slot for its use just
> before starting the AP.
>
> (The AP has to be part way along before it can do its own
> automatic-random-slb-slot-replacements from what I can tell.)
>
> The patches do not remove the race and still do sometimes fail to
> prevent getting a hang-up on a AP start. But it greatly decreased
> the rate of hangups in my testing. (So it is a good source of
> evidence about the original problem.)
>
> If EARLY_AP_STARTUP was supported and used, the AP startup would
> not have hang-up problems from mftb()%n_slbs based slb
> replacements for other threads.
>
> The patches are a hack, rather than a general/complete fix --and
> I do not expect to see them in FreeBSD. But they do help set up
> a better context for investigating other things.
The disabling of blocking duplicate paths in fdt_add_subnode_namelen
was done incorrectly. I'll replace the attachment after building
and testing. I think this is the explanation for the PowerMac11,2
shutdown -r or -p problems.
The code should have just disabled the return, more like:
if (offset >= 0)
#if 0
// Some Macintoshes have identical package-to-pathname results for
// multiple nodes of the same type and unit under the parent node.
// Avoid blocking this for fdt.
return -FDT_ERR_EXISTS;
#else
;
#endif
else if (offset != -FDT_ERR_NOTFOUND)
return offset;
Instead the messed up change did the "return offset;" and
so did not do the addition of the node, instead returning
the pre-existing one to be manipulated.
===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
More information about the freebsd-ppc
mailing list