linux-kernel - Re: [PATCH v5 1/9] arm64: dts: exynos: Add dts files for 64-bit Exynos5433 SoC

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Date:	Tue, 10 Mar 2015 10:31:03 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Mark Rutland <mark.rutland@....com>
Cc:	Chanwoo Choi <cwchoi00@...il.com>,
	"kgene@...nel.org" <kgene@...nel.org>,
	Marc Zyngier <Marc.Zyngier@....com>,
	"arnd@...db.de" <arnd@...db.de>, "olof@...om.net" <olof@...om.net>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	"inki.dae@...sung.com" <inki.dae@...sung.com>,
	"chanho61.park@...sung.com" <chanho61.park@...sung.com>,
	"sw0312.kim@...sung.com" <sw0312.kim@...sung.com>,
	"jh80.chung@...sung.com" <jh80.chung@...sung.com>,
	"ideal.song@...sung.com" <ideal.song@...sung.com>,
	"a.kesavan@...sung.com" <a.kesavan@...sung.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 1/9] arm64: dts: exynos: Add dts files for 64-bit
 Exynos5433 SoC

Hi Mark,

On 03/06/2015 09:18 PM, Chanwoo Choi wrote:
> Hi,
> 
> On 03/06/2015 08:40 PM, Mark Rutland wrote:

[snip]

>>
>>>>>>>> I take it CPUs boot at EL2?
>>>>>>
>>>>>> Do the CPUs boot at EL1 or EL2?
>>>>>
>>>>> Unfortunately, I cannot check the secure firmware for Exynos5433 SoC.
>>>>> I think that a few SoC provider probably would know it.
>>>>
>>>> I guess I asked the wrong question.
>>>>
>>>> Do CPUs enter the kernel at EL2 or at EL1?
>>>
>>> Could you give me a tip how to check the kernel at EL2 or EL1?
>>
>> Hmm... I thought we logged this but it looks like we don't.
>>
>> You could hack in a check of is_hyp_mode_available() and
>> is_hyp_mode_mismatched(). That will tell you if EL2/hyp is available,
>> and whether all CPUs enter at the same mode (mandatory per the boot
>> protocol).
> 
> OK, I'll try it.

I check the return value of is_hyp_mode_available() to catch whether EL1 or EL2. 

The is_hyp_mode_available() returns 'false' during kernel booting.
- __boot_cpu_mode[0]: 0xe11 (BOOT_CPU_MODE_EL1)
- __boot_cpu_mode[1]: 0x0

Best Regards,
Chanwoo Choi



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