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Biederman" To: David Woodhouse Cc: "Rafael J. Wysocki" , Thomas Gleixner , Ming Lei , LKML , Linux PM , Kexec Mailing List References: <4968818.GXAFRqVoOG@rjwysocki.net> <87h673zkhr.fsf_-_@email.froward.int.ebiederm.org> Date: Mon, 16 Dec 2024 12:21:01 -0600 In-Reply-To: (David Woodhouse's message of "Mon, 16 Dec 2024 18:14:17 +0000") Message-ID: <87bjxbzdyq.fsf@email.froward.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1tNFik-00FtDO-Lx;;;mid=<87bjxbzdyq.fsf@email.froward.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=72.198.198.28;;;frm=ebiederm@xmission.com;;;spf=pass X-XM-AID: U2FsdGVkX1+z7hsfZYbh2h99As8mJSOdcZfr7Fg2uXQ= X-Spam-Level: X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.4471] * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa07 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa07 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;David Woodhouse X-Spam-Relay-Country: X-Spam-Timing: total 316 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 11 (3.4%), b_tie_ro: 9 (3.0%), parse: 1.40 (0.4%), extract_message_metadata: 18 (5.7%), get_uri_detail_list: 1.43 (0.5%), tests_pri_-2000: 22 (7.0%), tests_pri_-1000: 3.7 (1.2%), tests_pri_-950: 1.60 (0.5%), tests_pri_-900: 1.02 (0.3%), tests_pri_-90: 77 (24.3%), check_bayes: 75 (23.8%), b_tokenize: 9 (2.8%), b_tok_get_all: 17 (5.5%), b_comp_prob: 2.1 (0.7%), b_tok_touch_all: 43 (13.6%), b_finish: 0.87 (0.3%), tests_pri_0: 167 (52.8%), check_dkim_signature: 0.50 (0.2%), check_dkim_adsp: 3.2 (1.0%), poll_dns_idle: 1.16 (0.4%), tests_pri_10: 2.1 (0.7%), tests_pri_500: 7 (2.1%), rewrite_mail: 0.00 (0.0%) Subject: Re: Does anyone actually use KEXEC_JUMP? X-SA-Exim-Connect-IP: 166.70.13.51 X-SA-Exim-Rcpt-To: kexec@lists.infradead.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, ming.lei@redhat.com, tglx@linutronix.de, rjw@rjwysocki.net, dwmw2@infradead.org X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Scanned: No (on out01.mta.xmission.com); SAEximRunCond expanded to false David Woodhouse writes: > It isn't broken. I know of it being used a few million times a week. > > There are corner cases which have never worked right, like the callee > putting a different return address for its next invocation, on the > stack *above* the address it 'ret's to. Which since the first kjump > patch has been the first word of the page *after* the swap page (and > is now fixed in my tree). But fundamentally it *does* work. > > I only started messing with it because I was working on > relocate_kernel() and needed to write a test case for it; the fact > that I know of it being used in production is actually just a > coincidence. Cool. I had the sense that the original developer never got around to using it, so I figured I should check. Mind if I ask what you know of it being used for? I had imagined it might be a way to call firmware code preventing the need to code of a specific interface for each type of firmware. Eric