[Xen-devel] [PATCH v2 01/18] mini-os: correct first free pfn

[Juergen Gross <jgross@xxxxxxxx>]

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@xxxxxxxx>
Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 arch/x86/mm.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm.c b/arch/x86/mm.c
index 51aa966..ae1036e 100644
--- 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 */
-- 
2.6.6


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