x86: introduce init_memory_mapping for 32bit #1

... so can we use mem below max_low_pfn earlier.

this allows us to move several functions more early instead of waiting
to after paging_init.

That includes moving relocate_initrd() earlier in the bootup, and kva
related early setup done in initmem_init. (in followup patches)

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 4 deletions

diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index bba8d57bd7d8..03007cada0d1 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -226,10 +226,8 @@ static void __init reserve_initrd(void)
         }
 
         /* We need to move the initrd down into lowmem */
-        ramdisk_target = max_pfn_mapped<<PAGE_SHIFT;
-        ramdisk_here = find_e820_area(min(ramdisk_target, end_of_lowmem>>1),
-                                 end_of_lowmem, ramdisk_size,
-                                 PAGE_SIZE);
+        ramdisk_here = find_e820_area(0, end_of_lowmem, ramdisk_size,
+                                         PAGE_SIZE);
 
         if (ramdisk_here == -1ULL)
                 panic("Cannot find place for new RAMDISK of size %lld\n",
@@ -433,8 +431,12 @@ void __init setup_arch(char **cmdline_p)
                 max_pfn = e820_end_of_ram();
         }
 
+        /* max_low_pfn get updated here */
         find_low_pfn_range();
 
+        /* max_pfn_mapped is updated here */
+        init_memory_mapping(0, (max_low_pfn << PAGE_SHIFT));
+
         reserve_initrd();
 
         dmi_scan_machine();