New patch to review for coreboot: x86: Make sure boot device is mapped below 4G

[Stefan Reinauer]

Stefan Reinauer ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/11121

-gerrit

commit b09bead7d87e92a911ee33412452d406935755ef
Author: Stefan Reinauer 
Date:   Tue Aug 4 11:14:17 2015 -0700

x86: Make sure boot device is mapped below 4G

On x86-64 the current way of calculating the base address
    of the boot device (SPI flash) gets an unwanted sign extension,
    making it live somewhere at the end of 64bit address space.

Enforce rom_base to be at the upper end of the 4G address space.

Change-Id: Ia81e82094d3c51f6c10e02b4b0df2f3e1519d39e
    Signed-off-by: Stefan Reinauer 
---
 src/arch/x86/mmap_boot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/arch/x86/mmap_boot.c b/src/arch/x86/mmap_boot.c
index 6c98954..53973f9 100644
--- a/src/arch/x86/mmap_boot.c
+++ b/src/arch/x86/mmap_boot.c
@@ -24,7 +24,7 @@
 #include <stdlib.h>

/* The ROM is memory mapped just below 4GiB. Form a pointer for the base. */
-#define rom_base ((void *)(uintptr_t)(-(int32_t)CONFIG_ROM_SIZE))
+#define rom_base ((void *)(uintptr_t)(0x100000000ULL-CONFIG_ROM_SIZE))

static const struct mem_region_device boot_dev =
    MEM_REGION_DEV_INIT(rom_base, CONFIG_ROM_SIZE);