From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5F6EFE77180 for ; Mon, 16 Dec 2024 18:25:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Subject:Content-Type: MIME-Version:Message-ID:In-Reply-To:Date:References:Cc:To:From:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=DI8N+uG9ECaO9MtUeDVcCbPw1YWgb8PFeENftVe0d2Y=; b=zW0LpCBxgC2epMPthpyrdyI3Dt umgxLMpxIXgUuFamDvjZIPMphjgYOySBnOENrwkXbDz1oz+ed+TzOXwdXO5M1j/7IVl+mTjklfYgL DTAzX8clTD7QSUnev4F6nEkFu5m8W8zpLxbFtkmkWJFi66N+JDpqFWUINWeBKM2aUhVeAljWguSBx uhQCorsVpvy6hYBU7NmF0TTxjtDyde4jJIyLHb+mcsc+isgMpnkDlGB2B1nool4dYMguO+9baxuTo CwDsFbvPdjatNOwH+49V4lFeHBe6TLRKhJvEqATnHPpPCQKtxnpmc7eQDgHEYTGFV7oWDl8RuhTZY mpjjg7HQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tNFmM-0000000AxfZ-3hhC; Mon, 16 Dec 2024 18:25:14 +0000 Received: from out01.mta.xmission.com ([166.70.13.231]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tNFin-0000000Ax0u-1Sxe; Mon, 16 Dec 2024 18:21:34 +0000 Received: from in01.mta.xmission.com ([166.70.13.51]:35192) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1tNFil-004lrv-IE; Mon, 16 Dec 2024 11:21:31 -0700 Received: from ip72-198-198-28.om.om.cox.net ([72.198.198.28]:49960 helo=email.froward.int.ebiederm.org.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1tNFik-00FtDO-Lx; Mon, 16 Dec 2024 11:21:31 -0700 From: "Eric W. 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) 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= 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241216_102133_388147_83683F98 X-CRM114-Status: GOOD ( 17.35 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org 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