From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Morse Subject: Re: of_reserved_mem()/kexec interaction Date: Tue, 2 Apr 2019 11:14:25 +0100 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org To: Roy Pledge Cc: Rob Herring , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" List-Id: devicetree@vger.kernel.org Hi Roy, On 01/04/2019 20:09, Roy Pledge wrote: > I'm trying to understand if memory reserved in the device tree via the > "reserved-memory" facility is preserved during a kexec system call, > i.e., is the memory at the same location with the contents undisturbed > when the new kernel starts? If the reservation is a static-allocation (so the address appears in the DT) then the new kernel should know this is reserved too, and not touch it. If its a dynamic-allocation, the address isn't in the DT, so the new kernel can't know. It will dynamically allocate a new reservation, which may be in a different place. If the data didn't matter at the first-boot, it probably doesn't matter over subsequent kexec either. As an outlier: the gic has some funny requirements around this. It needs to dynamically allocate a page during first-boot that is preserved over kexec. It does this using efi_mem_reserve_persistent(). Thanks, James