Re: ARM64:Porting xen to new hardware

[Julien Grall <julien.grall@arm.com>]

Hello,

On 03/10/17 08:05, bharat gohil wrote:
> 
> 
> On Fri, Sep 29, 2017 at 11:12 PM, Julien Grall <julien.grall@arm.com 
> <mailto:julien.grall@arm.com>> wrote:
> 
> 
> 
>     On 09/29/2017 09:15 AM, bharat gohil wrote:
> 
>         Hello
> 
> 
>     Hi,
> 
>     Please avoid top-posting.
> 
>         The patch didn't work in my case.
> 
> 
>     The patch will be useful only if the compatible string in the DT of
>     your UART is "snps,dw-apb-uart". What is the compatible string for it?
> 
> In my case, compatible string is "ns16550a".
> Thanks,

Hmmm, looking back at the conversation your dom0 command line is:

console=hvc0,921600n8 earlyprintk=xen debug ignore_loglevel rw 
root=/dev/mmcblk0p7

earlyprintk=xen will do nothing as there are no Xen specific earlyprintk 
for Arm. For Dom0, I would recommend to use same same earlyprintk 
options as you would use on baremetal.

This would allow you to get some early input if the kernel get stuck 
before the console has been setup.

Furthermore, on a previous e-mail it has been mentioned that your 
problem might be because Linux will disable what it thinks unused clock. 
A way to prevent that (at least for debugging) is using add 
'clk_ignore_unused' on the Linux command line.

If the 2 suggestions above does not work, then you would have to 
instrument the kernel. When the hypervisor is build with debug enabled, 
there are is set a debug hvc provided. A useful one is hvc 0xfffd. For 
all of them, you can look at do_debug_trap in arch/arm/traps.c.

I hope this will help.

Cheers,

-- 
Julien Grall

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