From mboxrd@z Thu Jan  1 00:00:00 1970
From: Shannon Zhao <shannon.zhao@linaro.org>
Subject: Re: About runtime service for Xen on ARM
Date: Wed, 26 Aug 2015 21:27:56 +0800
Message-ID: <55DDBEDC.4030403@linaro.org>
References: <55D5733B.4050804@huawei.com> <55DD3158.3080003@citrix.com>
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To: Julien Grall <julien.grall@citrix.com>, Shannon Zhao <zhaoshenglong@huawei.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>, Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>, Daniel Kiper <daniel.kiper@oracle.com>, "Huangpeng (Peter)" <peter.huangpeng@huawei.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, Christoffer Dall <christoffer.dall@linaro.org>
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Hi Julien,

Thanks for your reply. :)

On 2015/8/26 11:24, Julien Grall wrote:
>
>
> On 19/08/2015 23:27, Shannon Zhao wrote:
>> Hi Julien,
>
> Hi Shannon,
>
> Sorry for the late answer I was on holiday. In general it's better to CC
> multiple person and the mailing list as we may not be able to answer in
> short time or not know the answer.
>
> I've CCed the ML and few people which know better than me the status of
> EFI runtime.
>
>> Do you know the status of runtime service for Xen on ARM? Does it
>> support runtime service booting with DT? If not, is there a plan to
>> support it?
>
> There is no support of runtime EFI on ARM for now and I'm not aware of
> any short plan for this.
>
>> In addition, if you know this, does it support runtime service for Xen
>> on x86?
>
> There is some on-going work for EFI runtime on x86. I'm not sure if it
> has been upstream (CCed Daniel for this).
>
> Although, one of there is a fundamental difference between the UEFI boot
> on x86 and ARM. While the code is the same, on ARM the UEFI act as a
> stub and should not be able to communicate via exported variable with
> Xen (we clobber BSS just after the UEFI stub jump on the normal boot
> start).
>
> I know that the ARM EFI stub is using some shared variable with Xen (I
> have in mind the memory banks see bootinfo). We are very lucky that it's
> working because the variable is living in initdata which somehow is part
> of text (I'm not sure why) and not BSS.
> So we should either decide that the stub and xen should be able to
> communicate together or not.
>
> I would be in favor of the former but I don't know what are the view of
> the others.
>
> Regards,
>

-- 
Shannon