linux-kernel - Re: [PATCH v3 12/17] ARM64: ACPI: Check if it runs on Xen to enable or disable ACPI

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Message-ID: <56A87F77.8070506@linaro.org>
Date:	Wed, 27 Jan 2016 16:27:35 +0800
From:	Hanjun Guo <hanjun.guo@...aro.org>
To:	Shannon Zhao <zhaoshenglong@...wei.com>,
	linux-arm-kernel@...ts.infradead.org, ard.biesheuvel@...aro.org,
	mark.rutland@....com, stefano.stabellini@...rix.com,
	david.vrabel@...rix.com
Cc:	catalin.marinas@....com, will.deacon@....com,
	julien.grall@...rix.com, xen-devel@...ts.xen.org,
	devicetree@...r.kernel.org, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org, ian.campbell@...rix.com,
	shannon.zhao@...aro.org, peter.huangpeng@...wei.com
Subject: Re: [PATCH v3 12/17] ARM64: ACPI: Check if it runs on Xen to enable
 or disable ACPI

Hi Shannon,

On 2016/1/23 11:19, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@...aro.org>
>
> When it's a Xen domain0 booting with ACPI, it will supply a /chosen and
> a /hypervisor node in DT. So check if it needs to enable ACPI.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@...aro.org>
> ---
> CC: Hanjun Guo <hanjun.guo@...aro.org>
> ---
>   arch/arm64/kernel/acpi.c | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index d1ce8e2..4e92be0 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -67,10 +67,13 @@ static int __init dt_scan_depth1_nodes(unsigned long node,
>   {
>   	/*
>   	 * Return 1 as soon as we encounter a node at depth 1 that is
> -	 * not the /chosen node.
> +	 * not the /chosen node, or /hypervisor node when running on Xen.

The comment is bit misleading, we need to specify two mode, running on
Xen or not, if not on xen, then /chosen node is enough.

>   	 */
> -	if (depth == 1 && (strcmp(uname, "chosen") != 0))
> -		return 1;
> +	if (depth == 1 && (strcmp(uname, "chosen") != 0)) {
> +		if (!xen_initial_domain() || (strcmp(uname, "hypervisor") != 0))
> +			return 1;
> +	}
> +
>   	return 0;
>   }
>
> @@ -184,7 +187,8 @@ void __init acpi_boot_table_init(void)
>   	/*
>   	 * Enable ACPI instead of device tree unless
>   	 * - ACPI has been disabled explicitly (acpi=off), or
> -	 * - the device tree is not empty (it has more than just a /chosen node)
> +	 * - the device tree is not empty (it has more than just a /chosen node,
> +	 *   and a /hypervisor node when running on Xen)

and here too.

if that is addressed,

Acked-by: Hanjun Guo <hanjun.guo@...aro.org>

Thanks
Hanjun