Re: [Xen-devel] Problems running Xen 4.4 on OMAP5432 evm

["Kapania, Ashish" <akapania@xxxxxx>]

Hi Ian,

I apologize for causing any confusion. The xen.lds file I modified is generated 
and
hence not tracked by git. I had forgotten about the change and running "git 
status"
was not telling me that I modified the file. Another point I wanted to make was
that I always do a "make distclean" before rebuilding xen but the xen.lds file
does not get regenerated. I had to manually delete it to force regeneration.
Maybe thatâs a bug ?

I tried the Ctrl-A * 3 + press 'd' sequence and found that dom0 is in ABT mode.
I tried debugging a little with JTAG (My JTAG setup does not work well in HYP
Mode so I cannot debug xen with it) and found that the ABT happens in
Linux/arch/arm/boot/compressed/head.S's __setup_mmu code. The exact instruction
that causes the abort is a store instruction that is attempting to write a page
table entry to 0x80004000.

MMU stage 1 translation is disabled at this point so it looks like the
Stage 2 translation is not mapping 0x80004000 address. Is there some step that
I am missing that is suppose to tell xen to map the memory used by linux to
store page tables ?

Best,
Ashish

-----Original Message-----
From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxx] 
Sent: Tuesday, April 22, 2014 2:58 AM
To: Kapania, Ashish
Cc: xen-devel@xxxxxxxxxxxxx
Subject: Re: [Xen-devel] Problems running Xen 4.4 on OMAP5432 evm

On Tue, 2014-04-22 at 02:39 +0000, Kapania, Ashish wrote:
> Hi Ian,
> 
> I was able to make progress with Xen 4.4 release itself. The xen image 
> was being placed at VA 0x200000 (which is not a valid address on 
> OMAP5) so I had updated xen.lds to change this.

If you are going to randomly hack at the code and then report bugs then you 
*must* tell us exactly what you have changed. We are not mind readers.

>  It seems that was the wrong thing to do

Yes

> and was causing
> the problem (Does xen perform a VA to PA mapping for xen address space ?).

Yes, it uses paging in the normal way.

>  After
> undoing my changes, I was able to get further.
> 
> My latest xen log is shared below. Xen gets to the point where it says 
> loading Kernel but it does not look like dom0 linux is booting up as I 
> donât see any logs printed on uart. I have set "console=hvc0" in the 
> dom0 Bootargs. I am running linux 3.8.13 and am able to boot it by 
> itself so the Linux image is working.
> 
> I am hoping to get some suggestions from you on how to debug this further.

http://article.gmane.org/gmane.comp.emulators.xen.devel/196351 might shed some 
light.

My usual next step would be to press Ctrl-A three times and then press 'q' to 
see if I can identify the PC where dom0 has crashed or is stuck.

After that I would try adding some calls to xen_raw_printk in the kernel to see 
if I could identify how far the kernel was getting.

Perhaps someone who has worked with the omap platform can give more specific 
advise.

Ian.

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