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[34.85.221.182]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-6410e8f4f2esm2014058d50.0.2025.11.14.11.00.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Nov 2025 11:00:20 -0800 (PST) From: Pasha Tatashin To: akpm@linux-foundation.org, bhe@redhat.com, pasha.tatashin@soleen.com, rppt@kernel.org, jasonmiu@google.com, arnd@arndb.de, coxu@redhat.com, dave@vasilevsky.ca, ebiggers@google.com, graf@amazon.com, kees@kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: [PATCH v2 13/13] kho: Add Kconfig option to enable KHO by default Date: Fri, 14 Nov 2025 14:00:02 -0500 Message-ID: <20251114190002.3311679-14-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.52.0.rc1.455.g30608eb744-goog In-Reply-To: <20251114190002.3311679-1-pasha.tatashin@soleen.com> References: <20251114190002.3311679-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 23542140013 X-Stat-Signature: zbidykk6x86jt9uf8j375naem8kkkj1e X-Rspam-User: X-HE-Tag: 1763146821-539800 X-HE-Meta: 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 obLy6tEq yFfWi3GOiS4aHYaDHiVBr974AZUhlQcQmFDAeprrarJWMksZBlzjOMgkbqVGJDwuK+pYT+Y88qdi/qy9N+UvXQ2onJVVZxxrFuoKr+3lclIUYxXq5whCHCMtld9egkRxnF5EOeQcguj29bTRTFbHKg+dN+km71KeDgYAYWGihJyP9xPDvXpU0us1yTF1ZLYvkeIW5ZoVoO5wWLils5RAn1jCYN/InqyNTJK/P7NEpeypSLG3PX401H5rtbsKyCzb0Rda0+lIN1I5NQJuYHA9OJo0L++ZMphsajugYfrATdCSJtd/d8/XHH5YsIYxatkvCSK+g1pKXYyAdjTWkOLkqH0786Yqmhcxoqkts X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Currently, Kexec Handover must be explicitly enabled via the kernel command line parameter `kho=on`. For workloads that rely on KHO as a foundational requirement (such as the upcoming Live Update Orchestrator), requiring an explicit boot parameter adds redundant configuration steps. Introduce CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT. When selected, KHO defaults to enabled. This is equivalent to passing kho=on at boot. The behavior can still be disabled at runtime by passing kho=off. Signed-off-by: Pasha Tatashin Reviewed-by: Mike Rapoport (Microsoft) --- kernel/liveupdate/Kconfig | 14 ++++++++++++++ kernel/liveupdate/kexec_handover.c | 2 +- 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/kernel/liveupdate/Kconfig b/kernel/liveupdate/Kconfig index eae428309332..a973a54447de 100644 --- a/kernel/liveupdate/Kconfig +++ b/kernel/liveupdate/Kconfig @@ -37,4 +37,18 @@ config KEXEC_HANDOVER_DEBUGFS Also, enables inspecting the KHO fdt trees with the debugfs binary blobs. +config KEXEC_HANDOVER_ENABLE_DEFAULT + bool "Enable kexec handover by default" + depends on KEXEC_HANDOVER + help + Enable Kexec Handover by default. This avoids the need to + explicitly pass 'kho=on' on the kernel command line. + + This is useful for systems where KHO is a prerequisite for other + features, such as Live Update, ensuring the mechanism is always + active. + + The default behavior can still be overridden at boot time by + passing 'kho=off'. + endmenu diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index a7f876ece445..224bdf5becb6 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -52,7 +52,7 @@ union kho_page_info { static_assert(sizeof(union kho_page_info) == sizeof(((struct page *)0)->private)); -static bool kho_enable __ro_after_init; +static bool kho_enable __ro_after_init = IS_ENABLED(CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT); bool kho_is_enabled(void) { -- 2.52.0.rc1.455.g30608eb744-goog