From 9c9bb1c0ac6278a0c81c1191881f5a158855f29f Mon Sep 17 00:00:00 2001 From: Daniel Kiper Date: Thu, 10 Mar 2022 16:48:50 +0100 Subject: [PATCH] commands/i386/pc/sendkey: Fix "writing 1 byte into a region of size 0" build error MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Latest GCC may complain in that way: commands/i386/pc/sendkey.c: In function ‘grub_sendkey_postboot’: commands/i386/pc/sendkey.c:223:21: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=] 223 | *((char *) 0x41a) = 0x1e; | ~~~~~~~~~~~~~~~~~~^~~~~~ The volatile keyword addition helps and additionally assures us the compiler will not optimize out fixed assignments. Signed-off-by: Daniel Kiper Reviewed-by: Robbie Harwood --- grub-core/commands/i386/pc/sendkey.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/grub-core/commands/i386/pc/sendkey.c b/grub-core/commands/i386/pc/sendkey.c index af91cc835..184befabf 100644 --- a/grub-core/commands/i386/pc/sendkey.c +++ b/grub-core/commands/i386/pc/sendkey.c @@ -220,8 +220,8 @@ grub_sendkey_postboot (void) *flags = oldflags; - *((char *) 0x41a) = 0x1e; - *((char *) 0x41c) = 0x1e; + *((volatile char *) 0x41a) = 0x1e; + *((volatile char *) 0x41c) = 0x1e; return GRUB_ERR_NONE; } @@ -236,8 +236,8 @@ grub_sendkey_preboot (int noret __attribute__ ((unused))) oldflags = *flags; /* Set the sendkey. */ - *((char *) 0x41a) = 0x1e; - *((char *) 0x41c) = keylen + 0x1e; + *((volatile char *) 0x41a) = 0x1e; + *((volatile char *) 0x41c) = keylen + 0x1e; grub_memcpy ((char *) 0x41e, sendkey, 0x20); /* Transform "any ctrl" to "right ctrl" flag. */