[meta-ti] [oe] ti81xx-psp-linux-2.6.37: broken kernel with gcc > 4.5

Thilo Fromm fromm at dresearch-fe.de
Fri May 18 07:40:25 PDT 2012

Hello Koen,

>>>>>> sorry for the cross-post (openembedded-devel, meta-ti), I think this
>>>>>> affects both projects one way or the other.
>>>>>> Recently, meta-openembedded/toolchain-layer removed gcc-4.5. This means
>>>>>> with oe-core + meta-oe you now can choose between gcc-4.6 and gcc-4.7.
>>>>>> However, both compilers break the kernel we're using
>>>>>> (ti81xx-psp-linux-2.6.37).
>>>>> What happens when you disable the mailbox? AIUI you shouldn't need that on
>>>>> Ne/Ce.
>>>> How do I disable the mailbox?
>>> In the .config
>> Wait wait wait, according to drivers/staging/tidspbridge/Kconfig we
>> need OMAP_MBOX_FWK (i.e. "the mailbox") in order to use the DSP
>> bridge. Disabling it would mean cutting off our DSP. No way.
> Are you actually using dspbridge? Or are you using dsplink or syslink?

No, I was wrong. OMAP_MBOX_FWK is forced to "Y" in our config and I
thought DSPBRIDGE forced this. But DSPBRIDGE isn't even active in our
configuration. I cannot turn OMAP_MBOX_FWK off, it's forced to Y, and
I'm currently trying to figure out which part of
ti81xx-psp-linux-2.6.37's wicked configuration is causing this.

>>>> What do you mean by Ne/Ce?
>>> Netra/Centaurus, dm81xx, c6a81xx, am38xx, am39xx or whatever TI is calling it nowadays.
>> We're on a "TI DaVinci DM8148", featuring a cortex-a8 combined with a
>> C674x DSP.
> So a centaurus family SoC.

Thanks for the clarification :) TI didn't approach us with any of the
terms you mentioned. It's just DaVinci for them when they're talking
with us.

>> I think the only ones left without DSPs are AM-...
>> processors. So no, the DSP bridge (and therefore mailboxing) must
>> stay.
> See what I said above, I doubt you're using dspbridge.

You may be right; I didn't dig into DSP communication so far. Also,
DSPBRIDGE depends on OMAP3, which we don't have (dm8148 is a
"OMAP2PLUS"). So I was wrong with DSPBRIDGE forcing OMAP_MBOX_FWK.
OMAP_MBOX_FWK is just active and I can't switch it off.


Dipl.-Ing (FH) Thilo Fromm, MSc., Embedded Systems Architect
DResearch Fahrzeugelektronik GmbH
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