Re: [Xen-users] Running Xen on ARM Juno r0

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Thu, 2015-09-17 at 14:05 -0400, N Jain wrote:
> Hi Ian,
> 
> T0SZ value can not be 0 as ARMv8 spec specifies the table for its values
> based on supported PA size and page table granule.

It's useful to give chapter and verse from the ARMv8 ARM when making this
kind of claim, so everyone is on the same page.

Having dug about a bit myself it seems like the maximum size of the
TTBR_EL2 is 2^48 and therefore VTCR_EL2.T0SZ indeed needs to be at least
16, according to the pseudo code describing a PT walk at D4-1697 and the
description at D4-1663.

Is this what you are alluding to above?

> Also I am using Xen 4.5 release but not able to get pass Head.S. 

Like I said in my previous reply I suggest you use the development branch
until you have things working on your platform.

> Do you pass any command line arguments while booting Xen so this T0SZ
> value changes ?

No, this value is hard coded in the source and so it cannot be changed with
command line arguments.

Given you understand the value to be wrong have you not tried simply
changing this number to whatever you believe is correct e.g. 16? Did that
help?
 
> Can you please send me the compilation steps and booting instructions
> which you use to boot up Xen ?

I build it with a simple make and launch the resulting binary from the EFI
shell. There is nothing magic to it I'm afraid.

Ian.

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