Re: Dom0 kernel for Xen4.6 on R-Car H2 (LAGER)

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

On 22/10/15 16:07, Ferger, Max wrote:
> Hello,

Hi,

> 2) Dom0 kernel is coming up and showing messages:
> 
>> From: Julien Grall [mailto:julien.grall@citrix.com]
>> Sent: Wednesday, October 21, 2015 8:02 PM
>>
>> To be sure, even the patch I attached on the previous mail doesn't help
>> you to get the console?
> 
> The patch works. But now it is obsolete, and reverted.
> 
> My mistake was how I tried to configure the kernel:
> Following the OMAP wiki [1], which I think is a little misleading,
> I appended the CONFIG_XEN* and friends to .config, and called 'make',
> leading to the CONFIG_XEN*-flags to be overwritten by defaults.
> Once configured via menuconfig, Dom0 showed messages all right.

Linux tends to remove the CONFIG_* if it's not able to turn on it's
dependencies.

I usually double check after a 'make oldconfig'.

>> If so, the simplest way to investigate requires the serial driver in Xen
>> to be functional (IIRC it's not the case right now). If you got it, you
>> can type CTRL-a tree times and access to the Xen console.
> 
> This great tool works now.

>> If you have Xen built with debug=y, from the log you sent it seems to be
>> the case, you can use the asm instruction "hvc" to get Xen printing
>> useful information:
>>     - hvc 0xffff will dump the state of the vCPU
>>     - hvc 0xfffd will print the program counter
> 
> Nice to know.  Couldn't find it on the wiki, though.

I documented them in a talk I gave [1] but never took the opportunity to
wikify it.

I will try to do it on the next Document Day.

> I'll update the LAGER board wiki [2] with my findings.

That would be useful, thank you!

Regards,

[1] http://www.slideshare.net/xen_com_mgr/bsdcan-2015-how-to-port-your-bsd

-- 
Julien Grall