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[34.85.221.182]) by smtp.gmail.com with ESMTPSA id 00721157ae682-78822125317sm16468577b3.37.2025.11.14.07.54.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Nov 2025 07:54:14 -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 v1 12/13] kho: Add Kconfig option to enable KHO by default Date: Fri, 14 Nov 2025 10:53:57 -0500 Message-ID: <20251114155358.2884014-13-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.52.0.rc1.455.g30608eb744-goog In-Reply-To: <20251114155358.2884014-1-pasha.tatashin@soleen.com> References: <20251114155358.2884014-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: EA14618001D X-Stat-Signature: b1yj9oa7w4im88qoeredp4trh7z6m6sw X-Rspam-User: X-HE-Tag: 1763135655-480930 X-HE-Meta: U2FsdGVkX19wKN6rnKU7m3efmx78+/sj4te1ll+rYYuIJsZkgwcMkcjXJmAagYnt7k5vC+1d4KQcab7kljffm0m1ZT/y8+GVcvmBInd7gMybHEkJhLFYE1WWpknPZeW0qhjIsW2evA2ELfc3sPU/3tKxC19SswoywyqI4gr5KJJD0m1ABVABtPevLmWS9eXo/z0B+zlD5RH/TnmlDCzcyKfn1Kb97Z4QlbP82I5WapD+ndxom+k3f+oIkfvXxGzFMoo7MIC38vhoni0uGRIVaDQpDIpPgXF3Dt+l0yb1RDqo7lGYiZPl2NSKgv0kFqkWvF1Sr869rfGy8X7YID94lGV8O3lirBRGdNRicsvD4TjYbp+OwUT+QTQfqBFl7TK5ip775TPH8Cn57l1x8x8ropAoPu427UgtlOvkVZ0PgA3O4taLGSs+0sIU7TgRfTB4tPL+RQ4zFqOnJ5zGXV9FbDNQjCa4xlDJ6YsOWqqeumNeW9tTeCjMfgtVyWY6nwf56iyurc9e5K0PVtSokaDlbVko2l2WtDlMwGP+jL6DYQQabyF6X1iLGghjCEJ9puWo7G1siYBJtyJb0K6c8a6rwAzxwZZNvpgEm3EOnIyuBZJjfg5WnzFFO6H/jw2/xd9JsMkadWP8A0sEAZIvFhBaEjrHd+fhXt0NYKLFTSsXICudsze8TvX5/o0xgq2gbLdSohzdJv9nIm+COaSj31BR/VYINHXAzJU0r/ZVd563IOkFJr8CcECbVTGHVypmhLBuVdef4lSazmco/b1NjrimE/KRyAMHLteaL8fJaqptikLKgcTWEAB+1s1fiwIDaAZtTCe4DIy3c7s8YRhFqzGIg7mWEk8Fea8iEpOAUCV36+LgTBhFelo+kQBybaVqK1QOrlNYAToyOg4Jt1FAh7T9/aCwCeoYman4iEIbog8MbPc3sRfn70XDEDiU/w97zYSa08lriGIZXKU734VhLI5 //+qxvM5 YXs3wmGTshVYgDzVAUHfiMeEWIpNW34vVuPw904kBHHHFjGavj+EIC1BpQaFAQ2E9N0httMM1wQQ5okb0DvAVCKZ+piYDj97JlPR2wMfvw3eQ5gRo5ouSyzFOX0zKXWj8HivQpoyXwfE/FFWhc1oBdAroXZfNGMQUCQZg41Zy8bUgVMzyOiBuKuy9o7xsR/5kGmnCA7mfcA9keUtSy8BtRpq0N6OXAO3Lszp0AzpyMZWwNf4SbkFTEHSLcd3EHQ/TCJ3dlykZkVMDS2VvAjxfvMHYsp62scdBK/8VH+nacSoI1td+YOzjKh95SUq5UuO3m+wEjbtgHAAGxjo= 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 --- 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 87e9b488237d..a905bccf5f65 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -50,7 +50,7 @@ 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