Re: [PATCH] ARM: move firmware_ops to drivers/firmware

2013-11-18 Thread Christopher Covington 
Hi Catalin,

On 11/18/2013 12:30 PM, Catalin Marinas wrote:
[...]
> You can't run legacy AArch32 code at EL3 and have lower levels in AArch64
> mode (architectural constraint).

What prevents AArch32 code from running at EL3 and then requesting a reset to
AArch64 by writing to the Reset Management Register before sliding down to
lower exception levels?

Thanks,
Christopher

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Re: [PATCH] ARM: dts: Update arch timer node with clock frequency

2013-09-20 Thread Christopher Covington 
On 09/20/2013 04:17 AM, Marc Zyngier wrote:
> On 20/09/13 05:57, Yuvaraj Kumar wrote:
>> Resending it as it bounced from kernel mailing group
>>
>> On Wed, Sep 18, 2013 at 3:53 PM, Mark Rutland  wrote:
>>> [adding lakml]
>>>
>>> On Wed, Sep 18, 2013 at 11:11:53AM +0100, Yuvaraj Kumar C D wrote:
 Without the "clock-frequency" property in arch timer node, could able
 to see the below crash dump.
>>>
>>> Why does this cause the below crash specifically? What is CNTFRQ reading
>>> as?
>> Return value of arch_timer_get_cntfrq() is 0
>>>
>>> Your firmware or bootloader should set CNTFRQ -- setting the
>>> clock-frequency is a work-around for buggy firmware/bootloaders that
>>> should be avoided as far as possible.
>> Why kernel should depend on bootloader/firmware  to set CNTFRQ? Any
>> specific reasons?
> 
> Because the kernel can't set it if running non-secure. Only secure mode
> can do this (see the ARM ARM for details).

What software outside the kernel actually reads the CNTFRQ and why?

Thanks,
Christopher

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