From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iNJva-0002Gz-KV for barebox@lists.infradead.org; Wed, 23 Oct 2019 16:56:08 +0000 From: Ahmad Fatoum Date: Wed, 23 Oct 2019 18:55:57 +0200 Message-Id: <20191023165601.16441-2-a.fatoum@pengutronix.de> In-Reply-To: <20191023165601.16441-1-a.fatoum@pengutronix.de> References: <20191023165601.16441-1-a.fatoum@pengutronix.de> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH 2/6] efi: efi-image: don't mask x86 interrupts on boot To: barebox@lists.infradead.org Cc: Michael Olbrich , Ahmad Fatoum 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 Fixes: 55da0cf1 ("efi: add support for initrd loading") Signed-off-by: Ahmad Fatoum --- common/efi/efi-image.c | 1 - 1 file changed, 1 deletion(-) diff --git a/common/efi/efi-image.c b/common/efi/efi-image.c index 939663a6e250..9c66c9f882c5 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); -- 2.23.0 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox