[Xen-devel] [PATCH] linux: don't round up swiotlb slab count

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

This has been unnecessary for a long time, as xen_create_contiguous_region()
is no longer called on the whole area at once, and the rounding can (under
certain circumstances) prevent the kernel from successfully booting when a
larger than the default size is needed.

As usual, written and tested on 2.6.27-rc4 and made apply to the 2.6.18
tree without further testing.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: head-2008-08-22/lib/swiotlb-xen.c
===================================================================
--- head-2008-08-22.orig/lib/swiotlb-xen.c      2008-08-29 09:48:32.000000000 
+0200
+++ head-2008-08-22/lib/swiotlb-xen.c   2008-08-29 09:51:17.000000000 +0200
@@ -114,9 +114,6 @@ setup_io_tlb_npages(char *str)
                iotlb_nslabs = simple_strtoul(str, &str, 0) <<
                        (20 - IO_TLB_SHIFT);
                iotlb_nslabs = ALIGN(iotlb_nslabs, IO_TLB_SEGSIZE);
-               /* Round up to power of two (xen_create_contiguous_region). */
-               while (iotlb_nslabs & (iotlb_nslabs-1))
-                       iotlb_nslabs += iotlb_nslabs & ~(iotlb_nslabs-1);
        }
        if (*str == ',')
                ++str;
@@ -147,9 +144,6 @@ swiotlb_init_with_default_size(size_t de
        if (!iotlb_nslabs) {
                iotlb_nslabs = (default_size >> IO_TLB_SHIFT);
                iotlb_nslabs = ALIGN(iotlb_nslabs, IO_TLB_SEGSIZE);
-               /* Round up to power of two (xen_create_contiguous_region). */
-               while (iotlb_nslabs & (iotlb_nslabs-1))
-                       iotlb_nslabs += iotlb_nslabs & ~(iotlb_nslabs-1);
        }
 
        bytes = iotlb_nslabs * (1UL << IO_TLB_SHIFT);




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