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virtio: use u32, not bitmap for features

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It seemed like a good idea to use bitmap for features
in struct virtio_device, but it's actually a pain,
and seems to become even more painful when we get more
than 32 feature bits.  Just change it to a u32 for now.

Based on patch by Rusty.

Suggested-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
This commit is contained in:
Michael S. Tsirkin
2014-10-07 16:39:42 +02:00
parent d4024af56f
commit e16e12be34
16 changed files with 42 additions and 74 deletions
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22
tools/virtio/linux/virtio.h
View File

@@ -6,31 +6,11 @@
/* TODO: empty stubs for now. Broken but enough for virtio_ring.c */
#define list_add_tail(a, b) do {} while (0)
#define list_del(a) do {} while (0)
#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
#define BITS_PER_BYTE 8
#define BITS_PER_LONG (sizeof(long) * BITS_PER_BYTE)
#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
/* TODO: Not atomic as it should be:
* we don't use this for anything important. */
static inline void clear_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
*p &= ~mask;
}
static inline int test_bit(int nr, const volatile unsigned long *addr)
{
return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
}
/* end of stubs */
struct virtio_device {
void *dev;
unsigned long features[1];
u32 features;
};
struct virtqueue {

2
tools/virtio/linux/virtio_config.h
View File

@@ -2,5 +2,5 @@
#define VIRTIO_TRANSPORT_F_END 32
#define virtio_has_feature(dev, feature) \
test_bit((feature), (dev)->features)
(__virtio_test_bit((dev), feature))