Re: [Qemu-devel] [PATCH] net: Disable netmap backend when not supported

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, Feb 14, 2014 at 05:40:24PM +0100, Vincenzo Maffione wrote:
> This patch fixes configure so that netmap is not compiled in if the
> host doesn't support an API version >= 11.
> 
> Moreover, some modifications have been done to net/netmap.c in
> order to reflect the current netmap API (11).
> 
> Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
> ---
>  configure    |  3 +++
>  net/netmap.c | 57 ++++++++++++++-------------------------------------------
>  2 files changed, 17 insertions(+), 43 deletions(-)
> 
> diff --git a/configure b/configure
> index 88133a1..61eb932 100755
> --- a/configure
> +++ b/configure
> @@ -2118,6 +2118,9 @@ if test "$netmap" != "no" ; then
>  #include <net/if.h>
>  #include <net/netmap.h>
>  #include <net/netmap_user.h>
> +#if (NETMAP_API < 11) || (NETMAP_API > 15)
> +#error
> +#endif

Why error when NETMAP_API > 15?

> @@ -56,31 +58,6 @@ typedef struct NetmapState {
>      struct iovec        iov[IOV_MAX];
>  } NetmapState;
>  
> -#define D(format, ...)                                          \
> -    do {                                                        \
> -        struct timeval __xxts;                                  \
> -        gettimeofday(&__xxts, NULL);                            \
> -        printf("%03d.%06d %s [%d] " format "\n",                \
> -                (int)__xxts.tv_sec % 1000, (int)__xxts.tv_usec, \
> -                __func__, __LINE__, ##__VA_ARGS__);         \
> -    } while (0)
> -
> -/* Rate limited version of "D", lps indicates how many per second */
> -#define RD(lps, format, ...)                                    \
> -    do {                                                        \
> -        static int t0, __cnt;                                   \
> -        struct timeval __xxts;                                  \
> -        gettimeofday(&__xxts, NULL);                            \
> -        if (t0 != __xxts.tv_sec) {                              \
> -            t0 = __xxts.tv_sec;                                 \
> -            __cnt = 0;                                          \
> -        }                                                       \
> -        if (__cnt++ < lps) {                                    \
> -            D(format, ##__VA_ARGS__);                           \
> -        }                                                       \
> -    } while (0)
> -
> -
>  #ifndef __FreeBSD__
>  #define pkt_copy bcopy
>  #else

Why are you deleting this?

> @@ -237,7 +214,7 @@ static ssize_t netmap_receive(NetClientState *nc,
>          return size;
>      }
>  
> -    if (ring->avail == 0) {
> +    if (nm_ring_empty(ring)) {
>          /* No available slots in the netmap TX ring. */
>          netmap_write_poll(s, true);
>          return 0;
> @@ -250,8 +227,7 @@ static ssize_t netmap_receive(NetClientState *nc,
>      ring->slot[i].len = size;
>      ring->slot[i].flags = 0;
>      pkt_copy(buf, dst, size);
> -    ring->cur = NETMAP_RING_NEXT(ring, i);
> -    ring->avail--;
> +    ring->cur = ring->head = nm_ring_next(ring, i);
>      ioctl(s->me.fd, NIOCTXSYNC, NULL);
>  
>      return size;

Are these changes related to the NETMAP_WITH_LIBS macro?  Please do that
in a separate patch so we keep the version checking change separate from
the NETMAP_WITH_LIBS change.