From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Fleming Subject: Re: [PATCH v2 1/2] efi: esrt: use memremap not ioremap to access ESRT table in memory Date: Tue, 1 Mar 2016 23:30:40 +0000 Message-ID: <20160301233040.GA31476@codeblueprint.co.uk> References: <1455535953-5056-2-git-send-email-ard.biesheuvel@linaro.org> <20160218104407.GC2651@codeblueprint.co.uk> <20160218132824.GE2651@codeblueprint.co.uk> <20160218134324.GG2651@codeblueprint.co.uk> <20160218141544.GH2651@codeblueprint.co.uk> <20160218191624.GA1515@redhat.com> <20160226144114.GA7475@codeblueprint.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160226144114.GA7475-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Peter Jones Cc: Ard Biesheuvel , "linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , Leif Lindholm , Mark Rutland , "Baicar, Tyler" , Dave Young , Matthew Garrett List-Id: linux-efi@vger.kernel.org On Fri, 26 Feb, at 02:41:14PM, Matt Fleming wrote: > On Thu, 18 Feb, at 02:16:24PM, Peter Jones wrote: > > > > So the question I have is: would you rather chop up regions and reserve > > the space, or allocate a new copy and update the configuration table > > (after ExitBootServices()) to point to it? The latter makes it pretty > > easy to do from an API that all these drivers can use, and it makes the > > kexec case completely transparent. > > > > Up to you. > > I think it makes the most sense to chop up the regions we care about > (i.e. the ones we have drivers for) because not only does that save us > the effort of copying out the data on every kexec reboot, it also > prevents us from leaking each copy since we don't free them at the > moment. > > Then we just need to maintain a separate list of regions to free in > efi_free_boot_services() or have some other way to distinguish between > them. > > Oh, and save_runtime_map() would need updating to save Boot Services > regions too. I have a very rough draft of patches that implement this strategy on the 'experiemntal/efi-memmap' branch in the EFI tree if anyone is curious and wants to take a look. The series will be sent out soon. I wouldn't necessarily try running them or anything as there's a few things that I know are broken; ia64 build, EFI mixed mode boot, probably arm64 regressions. The upshot of the patch series is that there's a whole lot of code we can share for manipulating memory maps between all EFI architectures and by fixing this "reserve boot services regions" in a generic way it should mean kexec under EFI on arm64 should be fairly trivial to implement, along with ESRT, etc.