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Peter Anvin" , Peter Zijlstra , Pratyush Yadav , Rob Herring , Rob Herring , Saravana Kannan , Stanislav Kinsburskii , Steven Rostedt , Thomas Gleixner , Tom Lendacky , Usama Arif , Will Deacon , devicetree@vger.kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, changyuanl@google.com Subject: Re: [PATCH v4 00/14] kexec: introduce Kexec HandOver (KHO) Message-ID: References: <20250206132754.2596694-1-rppt@kernel.org> <20250206162939.a1f86fb835f1eeb7ed73ff1c@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On 02/08/25 at 07:23pm, Pasha Tatashin wrote: > On Fri, Feb 7, 2025 at 8:38 PM Baoquan He wrote: > > > > On 02/06/25 at 08:28pm, Pasha Tatashin wrote: > > > On Thu, Feb 6, 2025 at 7:29 PM Andrew Morton wrote: > > > > > > > > On Thu, 6 Feb 2025 15:27:40 +0200 Mike Rapoport wrote: > > > > > > > > > This a next version of Alex's "kexec: Allow preservation of ftrace buffers" > > > > > series (https://lore.kernel.org/all/20240117144704.602-1-graf@amazon.com), > > > > > just to make things simpler instead of ftrace we decided to preserve > > > > > "reserve_mem" regions. > > > > > > > > > > The patches are also available in git: > > > > > https://git.kernel.org/rppt/h/kho/v4 > > > > > > > > > > > > > > > Kexec today considers itself purely a boot loader: When we enter the new > > > > > kernel, any state the previous kernel left behind is irrelevant and the > > > > > new kernel reinitializes the system. > > > > > > > > I tossed this into mm.git for some testing and exposure. > > > > > > > > What merge path are you anticipating? > > > > > > > > Review activity seems pretty thin thus far? > > > > > > KHO is going to be discussed at the upcoming lsfmm, we are also > > > planning to send v5 of this patch series (discussed with Mike > > > Rapoport) in a couple of weeks. It will include enhancements needed > > > for the hypervisor live update scenario: > > > > So is this V4 still a RFC if v5 will be sent by plan? Should we hold the > > reviewing until v5? Or this series is a infrustructure building, v5 will > > add more details as you listed as below. I am a little confused. > > We will modify the existing patches and send as v5 because some > interfaces are going to be changed*. > > Otherwise, v5 will make KHO a lot more flexible as it will allow to > use the tree all the time while the system is running instead of only > once during the activation phase. > > * Changing interfaces is optional, but decision whether to change > will be discussed at Hypervisor Live Update on Feb 10th: > https://lore.kernel.org/all/26a4b7ca-93a6-30e2-923b-f551ced03d62@google.com/ Ah, this is what I would like to know about the difference between v4 and v5. Thanks for the information, and looking forward to seeing the v5 update. > > > > > > > > > 1. Allow nodes to be added to the KHO tree at any time > > > 2. Remove "activate" (I will also send a live update framework that > > > provides the activate functionality). > > > 3. Allow serialization during shutdown. > > > 4. Decouple KHO from kexec_file_load(), as kexec_file_load() should > > > not be used during live update blackout time. > > > 5. Enable multithreaded serialization by using hash-table as an > > > intermediate step before conversion to FDT. > > >