[Xen-devel] [PATCH 3/5] libxc: create unmapped initrd in domain builder if supported

[Juergen Gross <jgross@xxxxxxxx>]

In case the kernel of a new pv-domU indicates it is supporting an
unmapped initrd, don't waste precious virtual space for the initrd,
but allocate only guest physical memory for it.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 tools/libxc/xc_dom_core.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c
index b510bbd..bb668b1 100644
--- a/tools/libxc/xc_dom_core.c
+++ b/tools/libxc/xc_dom_core.c
@@ -1019,8 +1019,10 @@ int xc_dom_build_image(struct xc_dom_image *dom)
     if ( dom->kernel_loader->loader(dom) != 0 )
         goto err;
 
-    /* load ramdisk */
-    if ( dom->ramdisk_blob )
+    /* Load ramdisk if initial mapping required. */
+    if ( dom->ramdisk_blob &&
+         (!dom->parms.elf_notes[XEN_ELFNOTE_MOD_START_PFN].data.num ||
+          dom->ramdisk_seg.vstart) )
     {
         if ( xc_dom_build_ramdisk(dom) != 0 )
             goto err;
@@ -1059,10 +1061,28 @@ int xc_dom_build_image(struct xc_dom_image *dom)
     }
     if ( dom->alloc_bootstack )
         dom->bootstack_pfn = xc_dom_alloc_page(dom, "boot stack");
+
     DOMPRINTF("%-20s: virt_alloc_end : 0x%" PRIx64 "",
               __FUNCTION__, dom->virt_alloc_end);
     DOMPRINTF("%-20s: virt_pgtab_end : 0x%" PRIx64 "",
               __FUNCTION__, dom->virt_pgtab_end);
+
+    /* Prepare allocating unmapped memory. */
+    if ( dom->virt_pgtab_end )
+        dom->virt_alloc_end = dom->virt_pgtab_end;
+
+    /* Load ramdisk if no initial mapping required. */
+    if ( dom->ramdisk_blob && !dom->ramdisk_seg.vstart &&
+         dom->parms.elf_notes[XEN_ELFNOTE_MOD_START_PFN].data.num )
+    {
+        if ( xc_dom_build_ramdisk(dom) != 0 )
+            goto err;
+        dom->flags |= SIF_MOD_START_PFN;
+        dom->ramdisk_seg.vend = dom->ramdisk_seg.vend - 
dom->ramdisk_seg.vstart;
+        dom->ramdisk_seg.vstart = dom->ramdisk_seg.pfn;
+        dom->ramdisk_seg.vend += dom->ramdisk_seg.vstart;
+    }
+
     return 0;
 
  err:
-- 
2.1.4


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