Date: Thu, 10 Sep 2015 12:24:19 +0100 From: Mark Rutland <mark.rutland@arm.com> To: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Cc: Shannon Zhao <zhaoshenglong@huawei.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, "linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>, "Ian.Campbell@citrix.com" <Ian.Campbell@citrix.com>, "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>, "ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "leif.lindholm@linaro.org" <leif.lindholm@linaro.org>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, "julien.grall@citrix.com" <julien.grall@citrix.com>, "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org>, "matt.fleming@intel.com" <matt.fleming@intel.com>, "christoffer.dall@linaro.org" <christoffer.dall@linaro.org>, "jbeulich@suse.com" <jbeulich@suse.com>, "peter.huangpeng@huawei.com" <peter.huangpeng@huawei.com>, "shannon.zhao@linaro.org" <shannon.zhao@linaro.org> Subject: Re: [PATCH] efi/libstub/fdt: Standardize the names of EFI stub parameters Message-ID: <20150910112418.GC29293@leverpostej> In-Reply-To: <alpine.DEB.2.02.1509101116580.2672@kaball.uk.xensource.com> References: <1441874516-11364-1-git-send-email-zhaoshenglong@huawei.com> <20150910095208.GA29293@leverpostej> <alpine.DEB.2.02.1509101116580.2672@kaball.uk.xensource.com>
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> > Does Xen not talk to EFI itself and/or give the kernel a virtual EFI > > interface? > > Xen talks to EFI itself but the interface provided to dom0 is somewhat > different: there are no BootServices (Xen calls ExitBootServices before > running the kernel), and the RuntimeServices go via hypercalls (see > drivers/xen/efi.c). That's somewhat hideous; a non Xen-aware OS wouild presumably die if trying to use any runtime services the normal way? I'm not keen on describing things that the OS cannot use. Why can't Xen give a virtual EFI interface to Dom0 / guests? e.g. create pages of RuntimeServicesCode that are trivial assembly shims doing hypercalls, and plumb these into the virtual EFI memory map and tables? That would keep things sane for any guest, allow for easy addition of EFI features, and you could even enter the usual EFI entry point, simulate ExitBootServices(), SetVirtualAddressMap(), and allow the guest to make things sane for itself... Mark.
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