(cc Jason for awareness) On Tue, 31 Jan 2023 at 05:04, Jia He <justin.he@xxxxxxx> wrote: > > I met a hung task warning and then kernel was hung forever with latest > kernel on an Ampere Emag server. > > The root cause is kernel was hung when invoking an efi rts call to set > the RandomSeed variable during the booting stage. The arch_efi_call_virt > call (set_variable) was never returned and then caused the hung task error. > Given that EFI variables work on this platform (as far as I know), the problem may be that we are calling SetVariable() too early. Could you double check whether setting variables works as expected? You can use efibootmgr -t 10 as root (for example) to set the boot timeout, and check whether the new value is retained after a reboot (efibootmgr will print the current value for you) Could you also please share the kernel log up until the point where it hangs? > On the Emag server, efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE) > is returned with "true" > This is as expected: if the firmware does not expose the RT properties table, all runtime services are assumed to be available. > Fix it by introducing the efi_get_supported_rt_services() and then determine > to set or clear the runtime services bit of efi.flags. > > Jia He (2): > efi: libstub: Fix the retriving of supported rutime services > efi: Introduce efi_get_supported_rt_services() to get the runtime > services mask > > drivers/firmware/efi/arm-runtime.c | 5 ++++- > drivers/firmware/efi/efi.c | 28 +++++++++++++++++-------- > drivers/firmware/efi/libstub/efi-stub.c | 2 ++ > include/linux/efi.h | 1 + > 4 files changed, 26 insertions(+), 10 deletions(-) > > -- > 2.25.1 >
