From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matt Fleming <matt@codeblueprint.co.uk>
Subject: Re: [Xen-devel] efi_enabled(EFI_PARAVIRT) use
Date: Wed, 4 May 2016 12:36:13 +0100
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To: Shannon Zhao <zhaoshenglong@huawei.com>
Cc: Shannon Zhao <shannon.zhao@linaro.org>, Stephen Rothwell <sfr@canb.auug.org.au>, Jeremy Fitzhardinge <jeremy@goop.org>, Stefano Stabellini <sstabellini@kernel.org>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, Peter Zijlstra <peterz@infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "Luis R. Rodriguez" <mcgrof@kernel.org>, Xen Devel <Xen-devel@lists.xensource.com>, Borislav Petkov <bp@alien8.de>, linux-next@vger.kernel.org, Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
List-Id: xen-devel@lists.xenproject.org

On Tue, 03 May, at 09:45:22AM, Shannon Zhao wrote:
> > +static int __init fdt_find_uefi_params(unsigned long node, const char *uname,
> > +				       int depth, void *data)
> > +{
> > +	struct param_info *info = data;
> > +	int i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
> > +
> > +		if (depth != 1 || strcmp(uname, dt_params[i].uname) != 0) {
> > +			info->missing = dt_params[i].params[0].name;
> > +			continue;
> > +		}
> > +
> So here it needs to check whether the node is /hypervisor. If so, get
> the subnode "uefi". Like below:
> if (strcmp(uname, "hypervisor") == 0) {
> 	offset = of_get_flat_dt_subnode_by_name(node, "uefi");
> 	if (offset < 0)
> 		return 0;
> 	node = offset;
> }

Urgh, right.

How about giving dt_params a const char *subnode field and doing,

	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
		const char *subnode = dt_params[i].sub_node;

		if (depth != 1 || strcmp(uname, dt_params[i].uname) != 0) {
			info->missing = dt_params[i].params[0].name;
			continue;
		}

		if (subnode) {
			offset = of_get_flat_dt_subnode_by_name(node, subnode);
			if (offset < 0)
				return 0;
			node = offset;
		}

	...