mini-os: correct first free pfn

The first free pfn available for allocation is calculated by adding the
number of page table frames to the pfn of the first page table and
then the magic number 3 to account for start info page et al.

As the start info page, xenstore page and console page are allocated
_before_ the page tables leaving room for these pages behind the page
tables makes no sense.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

diff --git a/arch/x86/mm.c b/arch/x86/mm.c
index 51aa96624473cf11e1f7e9c56e07c7f53ed66860..ae1036ec135b987098e771725062ca4eb24fcd15 100644 (file)
--- a/arch/x86/mm.c
+++ b/arch/x86/mm.c
@@ -867,9 +867,8 @@ void arch_init_mm(unsigned long* start_pfn_p, unsigned long* max_pfn_p)
     printk("stack start: %p(VA)\n", stack);
     printk("       _end: %p(VA)\n", &_end);
 
-    /* First page follows page table pages and 3 more pages (store page etc) */
-    start_pfn = PFN_UP(to_phys(start_info.pt_base)) + 
-        start_info.nr_pt_frames + 3;
+    /* First page follows page table pages. */
+    start_pfn = PFN_UP(to_phys(start_info.pt_base)) + start_info.nr_pt_frames;
     max_pfn = start_info.nr_pages;
 
     /* We need room for demand mapping and heap, clip available memory */