Re: [Xen-devel] Debugging Dom0 on OMAP5

[Vaibhav Bedia <vaibhav.bedia@xxxxxxxxx>]

Hi Ian,

On Thu, Oct 24, 2013 at 4:18 AM, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> On Wed, 2013-10-23 at 20:13 -0400, Vaibhav Bedia wrote:
>
>> Looking at the logs i noticed that the initrd is located outside the
>> phys area that kernel
>> is aware of and hence getting ignored.
>>
>> [...]
>> [0.000000] INITRD: 0x83000000+0x01000000 is not a memory region -
>> disabling initrd
>>
>> In the bootargs i have specified the initrd
>
> Do you mean the bootargs given to Xen or the ones given to dom0? How
> exactly did you do this.
>

I specified that in the bootargs being passed to Dom0.
U-Boot# fdt set /chosen xen,dom0-bootargs \"console=hvc0,115200n8
vram=16M root=/dev/ram initrd=0x83000000,16M ramdisk_size=65536 rw
earlyprintk=xen lpj=61440 nohlt\"

>>  to be located to
>> 0x83000000 and that obviously isn't working. What is the right way to 
>> specify the initrd location to
>> Dom0? Does it depend on where Xen relocates the initrd?
>
> Xen itself chooses where the initrd lives in the guest physical address
> space, based on various constraints documented in
> linux/Documentation/arm/booting.txt. This stuff is a bit new so I
> suppose there could still be issues. Certainly if it is placing the
> initrd outside of the guest's RAM area then that is a issue!
>
> For this to work you (or your bootloader) need to be specifying the
> location of the initrd in the host memory space at boot time, Xen will
> then copy it into guest space and setup the DT given to dom0 to
> reference it.
>

Ok something odd happened just now. I formatted a micro-SD card to try
out a filesystem that.
I guess something went wrong in the formatting and that failed but the
initrd got mounted!

I think this happened because i replaced the initrd related stuff from
dom0-bootargs with the
ones for SD boot. To confirm this, i completely removed the root=<xyz>
stuff from dom0-bootargs
and now i can get the ramdisk to work fine.

So, is not specifying anything in the dom0-bootargs the right way to
make this thing work?

Regards,
Vaibhav

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