[Xen-devel] [PATCH 1 of 4] hvmloader: reduce minimum allocation alignment from 1024 bytes to 16

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1307026837 -3600
# Node ID 1f07d98d624ec828bd6483425adf204521175833
# Parent  f7493e7dd9daa6b25bade1f027702d2e61c326bb
hvmloader: reduce minimum allocation alignment from 1024 bytes to 16.

1024 bytes create a lot of wastage when the majority of allocations are of BIOS
table data structures which are generally happy with much lower alignment. I
conservatively chose 16 bytes.

Most callers pass 0 for the alignment anyway, for the rombios high code
allocation I kept it 1024 byte aligned since it was the only case that didn't
seem obviously ok with a smaller alignment.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r f7493e7dd9da -r 1f07d98d624e 
tools/firmware/hvmloader/32bitbios_support.c
--- a/tools/firmware/hvmloader/32bitbios_support.c      Thu Jun 02 15:09:24 
2011 +0100
+++ b/tools/firmware/hvmloader/32bitbios_support.c      Thu Jun 02 16:00:37 
2011 +0100
@@ -67,7 +67,7 @@ static uint32_t relocate_32bitbios(char 
      */
     reloc_size = reloc_off;
     printf("%d bytes of ROMBIOS high-memory extensions:\n", reloc_size);
-    highbiosarea = mem_alloc(reloc_size, 0);
+    highbiosarea = mem_alloc(reloc_size, 1024);
     BUG_ON(highbiosarea == NULL);
     printf("  Relocating to 0x%x-0x%x ... ",
            (uint32_t)&highbiosarea[0],
diff -r f7493e7dd9da -r 1f07d98d624e tools/firmware/hvmloader/util.c
--- a/tools/firmware/hvmloader/util.c   Thu Jun 02 15:09:24 2011 +0100
+++ b/tools/firmware/hvmloader/util.c   Thu Jun 02 16:00:37 2011 +0100
@@ -312,9 +312,9 @@ void *mem_alloc(uint32_t size, uint32_t 
     xen_pfn_t mfn;
     uint32_t s, e;
 
-    /* Align to at least one kilobyte. */
-    if ( align < 1024 )
-        align = 1024;
+    /* Align to at least 16 bytes. */
+    if ( align < 16 )
+        align = 16;
 
     s = (reserve + align) & ~(align - 1);
     e = s + size - 1;
@@ -366,9 +366,9 @@ void *scratch_alloc(uint32_t size, uint3
 {
     uint32_t s, e;
 
-    /* Align to at least one kilobyte. */
-    if ( align < 1024 )
-        align = 1024;
+    /* Align to at least 16 bytes. */
+    if ( align < 16 )
+        align = 16;
 
     s = (scratch_start + align - 1) & ~(align - 1);
     e = s + size - 1;

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