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authorAhmad Fatoum <a.fatoum@pengutronix.de>2019-10-23 18:55:57 +0200
committerSascha Hauer <s.hauer@pengutronix.de>2019-10-24 09:59:30 +0200
commit60101d8efc8036853345061c288b4789be4c3132 (patch)
treefb4fc38c985a8bc2c6375d0940412c2b6575a2a5
parent0ddc47db89b19baf6c085fc86537631126f3ff5f (diff)
downloadbarebox-60101d8efc8036853345061c288b4789be4c3132.tar.gz
efi: efi-image: don't mask x86 interrupts on boot
55da0cf1 ("efi: add support for initrd loading") introduced support for the Linux v3.6+ handover protocol[1]. As part of this change a x86 cli (Clear Interrupt Flag) instruction was introduced just prior to the jump into the kernel's EFI handover protocol entry point. While the normal Linux x86 boot protocols require that interrupts are masked on entry, this doesn't apply to the EFI stub, because the EFI stub itself is the one implementing the boot protocol and as such masks the interrupts itself[2]. EFI watchdogs may, and often are, implemented using a timer interrupt. Dropping the cli will allow monitoring the boot of the kernel up to it calling ExitBootServices. In absence of a hardware watchdog, this is the only watchdog available to users with EFI 1.0+, so it seems prudent to not make it even more useless. [1]: https://www.kernel.org/doc/Documentation/x86/boot.txt [2]: Linux v5.4-rc4, arch/x86/boot/compressed/eboot.c Cc: Michael Olbrich <mol@pengutronix.de> Fixes: 55da0cf1 ("efi: add support for initrd loading") Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
-rw-r--r--common/efi/efi-image.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/common/efi/efi-image.c b/common/efi/efi-image.c
index 939663a..9c66c9f 100644
--- a/common/efi/efi-image.c
+++ b/common/efi/efi-image.c
@@ -174,7 +174,6 @@ static inline void linux_efi_handover(efi_handle_t handle,
{
handover_fn handover;
- asm volatile ("cli");
handover = (handover_fn)((long)header->code32_start + 512 +
header->handover_offset);
handover(handle, efi_sys_table, header);