Re: [Xen-devel] Crash on boot with 2.6.37-rc8-git3

[M A Young <m.a.young@xxxxxxxxxxxx>]

On Mon, 10 Jan 2011, Konrad Rzeszutek Wilk wrote:

> > > Do you see any messages about 'Cannot find 20 bytes in node X' (where X
> > > I think is 0)?
> > I haven't spotted any such message.
> Try fiddling with the dom0_mem.. to see at what point it starts failing. Is
> this happening only on this machine or do you see it on other boxes too?
>
> Your E820 looks as so:
> BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
> BIOS-e820: 000000000009f000 - 00000000000a0000 (reserved)
> BIOS-e820: 0000000000100000 - 00000000df66d800 (usable)
> BIOS-e820: 00000000df66d800 - 00000000e0000000 (reserved)
> BIOS-e820: 00000000f8000000 - 00000000fc000000 (reserved)
> BIOS-e820: 00000000fec00000 - 00000000fec10000 (reserved)
> BIOS-e820: 00000000fed18000 - 00000000fed1c000 (reserved)
> BIOS-e820: 00000000fed20000 - 00000000fed90000 (reserved)
> BIOS-e820: 00000000feda0000 - 00000000feda6000 (reserved)
> BIOS-e820: 00000000fee00000 - 00000000fee10000 (reserved)
> BIOS-e820: 00000000ffe00000 - 0000000100000000 (reserved)
> BIOS-e820: 0000000100000000 - 0000000120000000 (usable)
>
> Which looks completly normal.. I am really at loss here. You could
> also sprinkle printk's around that code (or xen_raw_printk and inhibit
> the Linux kernel console output - that way you would only see the Xen
> and output from xen_raw_printk).
>
> Let me bootup 2.6.37 on a 4GB machine just to see if I am seeing this.
My next theory is that the issue is that the system is an alignment issue. 
The NODE DATA is put in the range 00000000df659800 to 00000000df66d7ff 
(the top end of the second "usable" chunk) and the problem come when it 
tries to write to the final 2K piece (00000000df66d000 to 
00000000df66d800 - 00000000df66d000 occurs on the stack) which hasn't been 
initialized properly because it isn't a 4K piece.
Does this sound plausible?

        Michael Young

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