Commit 7bd3643f authored by Pasha Tatashin's avatar Pasha Tatashin Committed by Andrew Morton
Browse files

kho: add Kconfig option to enable KHO by default 

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.

Link: https://lkml.kernel.org/r/20251114190002.3311679-14-pasha.tatashin@soleen.com


Signed-off-by: default avatarPasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: default avatarMike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: default avatarPratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent de51999e

kernel/liveupdate/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -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

kernel/liveupdate/kexec_handover.c

+1 −1
Original line number Diff line number Diff line
@@ -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)

{