From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [Xen-ARM] Modify the clock frequency for early printk Date: Thu, 17 Apr 2014 23:10:04 +0100 Message-ID: <5350513C.5060705@linaro.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: HyonYoung Choi , Anthony PERARD , "xen-devel@lists.xen.org" Cc: Meng Xu List-Id: xen-devel@lists.xenproject.org Hello, On 17/04/14 18:49, HyonYoung Choi wrote: > Hi Anthony and Julien, > > We are trying to run Xen 4.4 on the Arndale Octa board (Exynos 5420). > > The Xen and dom0's kernel is successfully loaded but Xen cannot start. > The last output information in serial console is Starting kernel. > > In order to figure out the reason, we tried to use the early_printk to > print out the message before console is initialized. However, the > message we got is some garbling message after the "Start kernel..." > message. Julien suggests this may be caused by the different rate of > clock on Exynos 5420 and Exynos 5250. > > We looked at the file xen/arch/arm/arm32/debug-exynos4210.inc, the clock > it chooses is MPLL 800MHz, but based on the output of our Exynos 5420 > board, our clock information is as follows: > > CPU: Exynos5420 Rev2.0 [Samsung SOC on SMP Platform Base on ARM CortexA15] > > APLL = 800MHz, KPLL = 600MHz > > MPLL = 532MHz, BPLL = 800MHz > > Our question is: > 1) Is there any patch for the debug-exynos4210.inc file to support our > board? > 2) How should we change the code in debug-exynos4210.inc file to make it > work on our board? > 3) We tried to find the manual of setting the clocks so that we can > change the following code accordingly. However, we cannot find it. Could > you please refer to us some manual to achieve that? In the patch I sent you earlier, can you try to replace EARLY_PRINTK_INIT_UART := y by EARLY_PRINTK_INIT_UART := n You have to clean the repo and recompile xen. Regards, -- Julien Grall