Re: [Xen-devel] new domain builder breaks compatibility

[Gerd Hoffmann <kraxel@xxxxxxx>]

Keir Fraser wrote:
> On 1/2/07 19:17, "John Levon" <levon@xxxxxxxxxxxxxxxxx> wrote:
> 
>>> --- tools/libxc/xc_dom_x86.c~ 2007-01-31 18:07:56.000000000 +0100
>>> +++ tools/libxc/xc_dom_x86.c 2007-02-01 10:02:08.000000000 +0100
>>> @@ -66,6 +66,7 @@
>>>  
>>>      extra_pages = dom->alloc_bootstack ? 1 : 0;
>>>      extra_pages += dom->extra_pages;
>>> +    extra_pages += 128; /* 512kB padding */
>> I've tested this along with a kernel change to only assume 2Mb
>> alignment, and it works on PAE and 64-bit now. Could you send a patch
>> upstream please? And update xen.h to clarify things?
> 
> I'll handle this and update xen.h.

Restoring the 4MB alignment is easy too, see attached patch (which also
fixes the 4MB alignment for virt_base).

cheers,
  Gerd

-- 
Gerd Hoffmann <kraxel@xxxxxxx>

---
 tools/libxc/xc_dom_x86.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: build-64-unstable-13762/tools/libxc/xc_dom_x86.c
===================================================================
--- build-64-unstable-13762.orig/tools/libxc/xc_dom_x86.c
+++ build-64-unstable-13762/tools/libxc/xc_dom_x86.c
@@ -66,11 +66,12 @@ static int count_pgtables(struct xc_dom_
 
     extra_pages = dom->alloc_bootstack ? 1 : 0;
     extra_pages += dom->extra_pages;
+    extra_pages += 128; /* 512kB padding */
     pages = extra_pages;
     for (;;)
     {
        try_virt_end = round_up(dom->virt_alloc_end + pages * PAGE_SIZE_X86,
-                               bits_to_mask(l1_bits));
+                               bits_to_mask(22)); /* 4MB alignment */
        dom->pg_l4 =
            nr_page_tables(dom->parms.virt_base, try_virt_end, l4_bits);
        dom->pg_l3 =
@@ -313,6 +314,9 @@ static int alloc_magic_pages(struct xc_d
     if (xc_dom_feature_translated(dom))
        dom->shared_info_pfn = xc_dom_alloc_page(dom, "shared info");
     dom->alloc_bootstack = 1;
+
+    /* 4MB align start address */
+    dom->parms.virt_base &= ~(((uint64_t)1<<22)-1);
     return 0;
 }
 

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