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SubjectRe: [PATCH] FRV: Specify the minimum slab/kmalloc alignment
On Wed, 28 May 2008 16:49:01 +0100
David Howells <dhowells@redhat.com> wrote:

> David Howells <dhowells@redhat.com> wrote:
>
> > +#define ARCH_KMALLOC_MINALIGN (sizeof(long) * 2)
> > +#define ARCH_SLAB_MINALIGN (sizeof(long) * 2)
>
> This doesn't work if SLAB is selected and slab debugging is enabled as these
> are passed to the preprocessor.
>

So.. like this?

From: David Howells <dhowells@redhat.com>

Specify the minimum slab/kmalloc alignment to be 8 bytes. This fixes a
crash when SLOB is selected as the memory allocator. The FRV arch needs
this so that it can use the load- and store-double instructions without
faulting. By default SLOB sets the minimum to be 4 bytes.

We need to use literal constants here as slab evaluates these within cpp.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

include/asm-frv/mem-layout.h | 7 +++++++
1 file changed, 7 insertions(+)

diff -puN include/asm-frv/mem-layout.h~frv-specify-the-minimum-slab-kmalloc-alignment include/asm-frv/mem-layout.h
--- a/include/asm-frv/mem-layout.h~frv-specify-the-minimum-slab-kmalloc-alignment
+++ a/include/asm-frv/mem-layout.h
@@ -31,6 +31,13 @@

#define PAGE_MASK (~(PAGE_SIZE-1))

+/*
+ * the slab must be aligned such that load- and store-double instructions don't
+ * fault if used
+ */
+#define ARCH_KMALLOC_MINALIGN 8 /* (sizeof(long) * 2) */
+#define ARCH_SLAB_MINALIGN 8 /* (sizeof(long) * 2) */
+
/*****************************************************************************/
/*
* virtual memory layout from kernel's point of view
_


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