Re: [Minios-devel] Regarding Mini-os boot up on xen arm

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-12-21 at 13:41 +0000, Misra Pankaj Kumar (RBEI/EEA2) wrote:
> -----UrsprÃngliche Nachricht-----
> Von: minios-devel-bounces@xxxxxxxxxxxxxxxxxxxx [mailto:minios-devel-bounc
> es@xxxxxxxxxxxxxxxxxxxx] Im Auftrag von Misra Pankaj Kumar (RBEI/EEA2)
> Gesendet: Montag, 21. Dezember 2015 13:02
> An: minios-devel@xxxxxxxxxxxxxxxxxxxx
> Betreff: Re: [Minios-devel] Regarding Mini-os boot up on xen arm
> 
> > -----UrsprÃngliche Nachricht-----
> > Von: Ian Campbell [mailto:ian.campbell@xxxxxxxxxx]
> > Gesendet: Freitag, 18. Dezember 2015 15:01
> > An: Misra Pankaj Kumar (RBEI/EEA2) <Pankaj.Kumar@xxxxxxxxxxxx>; 
> > minios-devel@xxxxxxxxxxxxxxxxxxxx
> > Betreff: Re: [Minios-devel] Regarding Mini-os boot up on xen arm
> > 
> > On Fri, 2015-12-18 at 13:48 +0000, Misra Pankaj Kumar (RBEI/EEA2)
> > wrote: 
> > 
> > Please don't top post.
> > > Thanks Ian for quick response.
> > > 
> > > My hardware is odroid xu4, so here it should be r2 register populated
> > > by Xen.
> > > Can you please point me to the code which passes this address to r2. 
> > 
> > SeeÂtools/libxc/xc_dom_arm.c (hopefully you tried using grep etc to
> > answer before asking).
> 
> Here I found a comment in this file, before updating r2 register, as :
> 
>       ÂÂÂÂ/* ATAGS/DTB: We currently require that the guest kernel to be
>       ÂÂÂÂÂ* using CONFIG_ARM_APPENDED_DTB. Ensure that r2 does not look
>       ÂÂÂÂÂ* like a valid pointer to a set of ATAGS or a DTB.
>       ÂÂÂÂÂ*/
>       ÂÂÂÂctxt->user_regs.r2_usr = dom->devicetree_blob ?
>       ÂÂÂÂÂÂÂÂdom->devicetree_seg.vstart : 0xffffffff;
> 
> 
> Does it mean that DTB pointer is dummy ?

No, this comment is out of date. These days we strongly recommend using the
toolstack generated DTB.

Using an appended DTB is, in theory, still possible, but you really need to
know what you are doing since it must match various aspects of the domain
cfg file.

> Value loaded in r2 here is 48000000.
> If we subtract offset 3fc00000 from it we get 08400000, which is the
> virtual address of DTB.
> It fails while de-referencing this pointer.
> Is it a valid address? Or the DTB contents are valid ?

I don't know, I'm afraid you will need to debug.

> I am providing RAM size as 256MB and Max as 512 MB.

I recommend using size and max the same, at least to start with.

> > > As its failing in my case
> > > (d3) Virtual -> physical offset = 3fc00000
> > > (d3) Checking DTB at 08400000...
> > > (d3) Fault handler at 004081ac called (prefetch_abort)
> > 
> > Which version of mini-os are you using? IIRC not all of the patches
> > have been applied toÂgit://xenbits.xen.org/mini-os.git. 
> I am using following repo :
> https://github.com/talex5/xen
> where are the patches available?

They were posted to the list.

Ian.

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