[PATCH] kexec: don't act as EFI chainloader if noefi.
chrisko at google.com
Wed Oct 17 16:41:39 PDT 2018
From: Christopher Koch <chrisko at google.com>
An EFI-booted Linux kernel will commit a virtual memory map in
efi_enter_virtual_mode, which is only done if
efi_enabled(EFI_RUNTIME_SERVICES). This can be disabled by adding noefi
to the command line.
kexec's setup_efi_state will then pass a memmap_size of 0 to the next
A Linux kernel cannot handle a memmap_size of 0 given by its bootloader:
efi_memblock_x86_reserve_range divides by the memmap_size and hits a
divide by 0 error.
When the 1st kernel is booted with noefi, it should not even attempt to
pass EFI information to any kexec'd kernel.
Signed-off-by: Christopher Koch <chrisko at google.com>
arch/x86/kernel/kexec-bzimage64.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 278cd07228dd..8ab4ffb901ce 100644
@@ -179,6 +179,14 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
+ * If we booted with noefi on the command line, we never committed a
+ * virtual memory map. It makes no sense to act as an EFI chainloader in
+ * that case.
+ if (!efi_enabled(EFI_RUNTIME_SERVICES))
+ return 0;
ei->efi_loader_signature = current_ei->efi_loader_signature;
ei->efi_systab = current_ei->efi_systab;
ei->efi_systab_hi = current_ei->efi_systab_hi;
More information about the kexec