From mboxrd@z Thu Jan 1 00:00:00 1970 From: stefano.stabellini@eu.citrix.com (Stefano Stabellini) Date: Mon, 18 Jan 2016 15:07:58 +0000 Subject: [PATCH v2 11/16] ARM64: ACPI: Check if it runs on Xen to enable or disable ACPI In-Reply-To: <20160118104142.GC21067@leverpostej> References: <1452840929-19612-1-git-send-email-zhaoshenglong@huawei.com> <1452840929-19612-12-git-send-email-zhaoshenglong@huawei.com> <20160118104142.GC21067@leverpostej> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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.