Subject: Re: visible memory seems wrong in kexec crash dump kernel

From: Scott Wood <[email-masked]>
Date: Wed, 31 Jul 2013 11:50:50 -0500

On 07/31/2013 11:40:05 AM, Friesen, Christopher wrote:
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> From: Scott Wood [[email-masked]]
> Sent: Monday, July 29, 2013 5:10 PM
> To: Friesen, Christopher
> Cc: Michael Ellerman; [email-masked]; Paul Mackerras; =20
> [email-masked]; Vivek Goyal
> Subject: Re: visible memory seems wrong in kexec crash dump kernel
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> On 07/13/2013 01:30:50 AM, Chris Friesen wrote:
> > The upshot is that there seems to be a number of things that could =20
> be
> > improved:
> >
> > 1) kexec should accept "/memory" and not just "/memory@"
> > 2) lmb_reserve() should really respect the crashkernel memory limit
> > 3) the freescale stuff really shouldn't assume it can map things
> > wherever it feels like
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> What "board-specific freescale code" are you referring to?
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> -Scott
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> Sorry for the crappy quoting, I'm using a web outlook portal.
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> I've switched employers so I don't have access to the exact details =20
> any more.  The system in question was a Kontron AM4150 which uses the =20
> P5020.  As I recall, one of the Freescale drivers (I think it was the =20
> buffer or queue manager that the network driver makes use of) was =20
> attempting to call lmb_reserve() with a base address in the 4GB range =20
> even though the recovery kernel was limited to 224MB of memory.

That's not "board specific" code, and it's not even mainline Linux =20
code.  Unfortunately none of the datapath stuff is upstream, still.

> While I've got your attention, the other thing that I found was that =20
> the "dpa" network driver didn't properly work in a kexec'd kernel =20
> even when given lots of memory.  It would work for a little bit and =20
> then hang.

I'm not particularly surprised by this.  It doesn't help that there's =20
no way to do a device reset. :-(

Issues with Freescale SDK code should be reported on =20
https://community.freescale.com/, to [email-masked], or to your =20
FAE.

-Scott=