1 files changed, 10 insertions, 1 deletions

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 48385c1074a5..8344dd2f310a 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -399,8 +399,13 @@ NEXT_PAGE(level3_ident_pgt)
         .quad   level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
         .fill   511, 8, 0
 NEXT_PAGE(level2_ident_pgt)
-        /* Since I easily can, map the first 1G.
+        /*
+         * Since I easily can, map the first 1G.
          * Don't set NX because code runs from these pages.
+         *
+         * Note: This sets _PAGE_GLOBAL despite whether
+         * the CPU supports it or it is enabled.  But,
+         * the CPU should ignore the bit.
          */
         PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
 #else
@@ -431,6 +436,10 @@ NEXT_PAGE(level2_kernel_pgt)
          * (NOTE: at +512MB starts the module area, see MODULES_VADDR.
          *  If you want to increase this then increase MODULES_VADDR
          *  too.)
+         *
+         *  This table is eventually used by the kernel during normal
+         *  runtime.  Care must be taken to clear out undesired bits
+         *  later, like _PAGE_RW or _PAGE_GLOBAL in some cases.
          */
         PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
                 KERNEL_IMAGE_SIZE/PMD_SIZE)