From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shannon Zhao Subject: Re: [PATCH v2 11/16] ARM64: ACPI: Check if it runs on Xen to enable or disable ACPI Date: Tue, 19 Jan 2016 16:41:11 +0800 Message-ID: <569DF6A7.8030709@huawei.com> References: <1452840929-19612-1-git-send-email-zhaoshenglong@huawei.com> <1452840929-19612-12-git-send-email-zhaoshenglong@huawei.com> <20160118104142.GC21067@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stefano Stabellini , Mark Rutland Cc: catalin.marinas-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, stefano.stabellini-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org, david.vrabel-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org, julien.grall-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org, xen-devel-GuqFBffKawuEi8DpZVb4nw@public.gmane.org, linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, shannon.zhao-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, peter.huangpeng-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, Ian Campbell List-Id: devicetree@vger.kernel.org On 2016/1/18 23:07, Stefano Stabellini wrote: > On Mon, 18 Jan 2016, Mark Rutland wrote: >> > On Fri, Jan 15, 2016 at 02:55:24PM +0800, Shannon Zhao wrote: >>> > > From: Shannon Zhao >>> > > >>> > > 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 >>> > > --- >>> > > 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. >>> > > */ >>> > > - 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; >>> > > } >> > >> > As this is changing the semantic of an "empty" DT, we should consider >> > now if there's anything else that might also need to exist in an "empty" >> > DT. We don't want to change this again in future if we don't have to, >> > given the compatiblity nightmare that's sure to result. >> > >> > We should also consider if the "hypervisor" node name is sufficient (I >> > think it is, but let's not assume anything). >>>From Xen point of view I think it is enough: real hardware is described > in ACPI anyway and anything hypervisor related can be done via > hypercalls once Xen support is discovered, for which the hypervisor node > is sufficient. Yes, I think the hypervisor node is sufficient for current Xen ACPI support. -- Shannon