1 files changed, 11 insertions, 2 deletions

diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 130711f1454b..41bb130c31db 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -60,16 +60,25 @@ int acpi_save_state_mem(void)
         header->video_mode = saved_video_mode;
 
         header->wakeup_jmp_seg = acpi_wakeup_address >> 4;
+
+        /*
+         * Set up the wakeup GDT.  We set these up as Big Real Mode,
+         * that is, with limits set to 4 GB.  At least the Lenovo
+         * Thinkpad X61 is known to need this for the video BIOS
+         * initialization quirk to work; this is likely to also
+         * be the case for other laptops or integrated video devices.
+         */
+
         /* GDT[0]: GDT self-pointer */
         header->wakeup_gdt[0] =
                 (u64)(sizeof(header->wakeup_gdt) - 1) +
                 ((u64)(acpi_wakeup_address +
                         ((char *)&header->wakeup_gdt - (char *)acpi_realmode))
                                 << 16);
-        /* GDT[1]: real-mode-like code segment */
+        /* GDT[1]: big real mode-like code segment */
         header->wakeup_gdt[1] =
                 GDT_ENTRY(0x809b, acpi_wakeup_address, 0xfffff);
-        /* GDT[2]: real-mode-like data segment */
+        /* GDT[2]: big real mode-like data segment */
         header->wakeup_gdt[2] =
                 GDT_ENTRY(0x8093, acpi_wakeup_address, 0xfffff);