From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shannon Zhao Subject: Re: efi_enabled(EFI_PARAVIRT) use Date: Sat, 30 Apr 2016 22:04:03 +0800 Message-ID: <5724BB53.40202@linaro.org> References: <20160429142020.4499e185@canb.auug.org.au> <20160429063936.GA28320@gmail.com> <20160429143931.GG2839@codeblueprint.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-next-owner@vger.kernel.org To: Stefano Stabellini Cc: Matt Fleming , Ingo Molnar , Stephen Rothwell , "Luis R. Rodriguez" , Jeremy Fitzhardinge , Konrad Rzeszutek Wilk , Stefano Stabellini , Xen Devel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Ard Biesheuvel , Borislav Petkov List-Id: xen-devel@lists.xenproject.org On 2016=E5=B9=B404=E6=9C=8829=E6=97=A5 23:37, Stefano Stabellini wrote: > On Fri, 29 Apr 2016, Stefano Stabellini wrote: >> On Fri, 29 Apr 2016, Matt Fleming wrote: >>> On Fri, 29 Apr, at 11:34:45AM, Stefano Stabellini wrote: >>>> On Fri, 29 Apr 2016, Ingo Molnar wrote: >>>>> Also, it would be nice to have all things EFI in a single tree, t= he conflicts are=20 >>>>> going to be painful! There's very little reason not to carry this= kind of commit: >>>>> >>>>> arch/arm/xen/enlighten.c | 6 +++++ >>>>> drivers/firmware/efi/arm-runtime.c | 17 +++++++++----- >>>>> drivers/firmware/efi/efi.c | 45 ++++++++++++++++++++++++= ++++++++------ >>>>> 3 files changed, 56 insertions(+), 12 deletions(-) >>>>> >>>>> in the EFI tree. >>>> >>>> That's true. I'll drop this commit from xentip and let Matt pick i= t up >>>> or request changes as he sees fit. >>> >>> One small change I think would be sensible to make is to expand >>> EFI_PARAVIRT into a few more bits to clearly indicate the quirks on >>> Xen, and in the process, to delete EFI_PARAVIRT. >>> >>> That should address Ingo's major concern, and also make it much eas= ier >>> to rework the code in a piecemeal fashion. >>> >>> Could somebody enumerate the things that make Xen (dom0) different = on >>> arm* compared with bare metal EFI boot? The list I made for x86 was= , >>> >>> 1. Has no EFI memory map >>> 2. Runtime regions do not need to be mapped >>> 3. Cannot call SetVirtualAddressMap() >>> 4. /sys/firmware/efi/fw_vendor is invisible >>> >>> The first maps to not setting EFI_MEMMAP, the second to not setting >>> EFI_RUNTIME. If we add EFI_ALREADY_VIRTUAL and EFI_FW_VENDOR_INVISI= BLE >>> to efi.flags that should cover everything on x86. Does arm* require >>> anything else? >> >> Xen on ARM is different, the impact should be limited: >> >> - there are no BootServices (ExitBootServices has already been calle= d) >> - RuntimeServices go via hypercalls >> >> The UEFI memory map is still available at an address specified on de= vice >> tree like on native, but the compatibility string is different >> ("xen,uefi-mmap-start") to clarify that we are booting on Xen rather >> than native. >> >> That's pretty much it, Shannon please confirm. >=20 > This is to say that Xen on ARM might only need EFI_RUNTIME. >=20 Yes, it needs EFI_RUNTIME_SERVICES. Thanks, --=20 Shannon