From mboxrd@z Thu Jan  1 00:00:00 1970
From: Shannon Zhao <shannon.zhao@linaro.org>
Subject: Re: efi_enabled(EFI_PARAVIRT) use
Date: Sun, 1 May 2016 11:24:18 +0800
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Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>, Stefano Stabellini <sstabellini@kernel.org>, Ingo Molnar <mingo@kernel.org>, Stephen Rothwell <sfr@canb.auug.org.au>, "Luis R. Rodriguez" <mcgrof@kernel.org>, Jeremy Fitzhardinge <jeremy@goop.org>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Xen Devel <Xen-devel@lists.xensource.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>, Peter Zijlstra <peterz@infradead.org>, linux-next@vger.kernel.org, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Borislav Petkov <bp@alien8.de>
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On 2016=E5=B9=B405=E6=9C=8801=E6=97=A5 04:44, Matt Fleming wrote:
>> While I still have a question, in this patch we use
>> > efi_enabled(EFI_PARAVIRT) as a condition to make fdt_find_uefi_par=
ams()
>> > and efi_get_fdt_params() execute different ways. So it needs to fi=
nd a
>> > new condition for that if we need to get rid of EFI_PARAVIRT. One =
I
>> > think is that xen_initial_domain() check. Is that fine?
> Hmm... why do you actually need to check whether you're running on a
> PV machine in fdt_find_uefi_params()?
Because the UEFI params for Dom0 are located under /hypervisor/uefi nod=
e
instead of /chosen. So it needs to check whether it's a Dom0 then searc=
h
and parse different node with different params arrays.

> Can't you infer that from the DT
> params you discover?
>=20

> I could understand maybe only accepting the "xen,uefi-system-table"
> property if IS_ENABLED(CONFIG_XEN) but surely you don't also need to
> filter based on whether you're booting a PV kernel?
>=20
> Let me put it this way: when would you see "xen,uefi-system-table" an=
d
> *not* be booting a PV kernel?
So it still needs add another check to firstly parse the fdt to see if
there is "xen,uefi-system-table" under /hypervisor/uefi node, right? I
think it's a bit redundant compared with xen_initial_domain().

Thanks,
--=20
Shannon