On 10/17/18 at 04:41pm, Chris Koch wrote: > From: Christopher Koch <chrisko@xxxxxxxxxx> > > 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 > kernel. > > 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@xxxxxxxxxx> > --- > 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 > --- a/arch/x86/kernel/kexec-bzimage64.c > +++ b/arch/x86/kernel/kexec-bzimage64.c > @@ -179,6 +179,14 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr, > if (efi_enabled(EFI_OLD_MEMMAP)) > return 0; > > + /* > + * 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; > + Previously there was a report from Mike Galbraith <efault@xxxxxx> for the case efi=noruntime, I was doing some cleanup for the kexec_file_load efi code path, but I'm occupied with some other thing, that is delayed. I think your patch looks good, can you add more words in the code comment about efi=noruntime, also maybe mention if one want to use kexec reboot in case noefi/noruntime he should pass acpi_rsdp= param in 2nd kernel cmdline. > 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; > -- > 2.19.1.331.ge82ca0e54c-goog > > > _______________________________________________ > kexec mailing list > kexec@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/kexec Thanks Dave _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
