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Date: Fri, 18 Dec 2009 12:32:37 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] osdep: Fix runtime failure on older Linux
	kernels
References: <1261129507-13244-1-git-send-email-andre.przywara@amd.com>
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To: Andre Przywara <andre.przywara@amd.com>
Cc: qemu-devel@nongnu.org

Am 18.12.2009 10:45, schrieb Andre Przywara:
> If QEMU finds newer kernel header files on compilation time, it will use
> advertised features like pipe2 or SOCK_CLOEXEC by just doing a compile test.
> If later the executables are executed on an older kernel (<2.6.27,
> like Xen Dom0 2.6.18), then QEMU will fail on opening sockets and creating
> pipes and returns the rather unspecific "qemu_init_main_loop failed".
> This patch fixes this by checking the return values of these calls
> for EINVAL and ENOSYS and falling back to the older versions automatically.
> 
> Signed-off-by: Andre Przywara <andre.przywara@amd.com>
> ---
>  osdep.c |   18 ++++++++++++------
>  1 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/osdep.c b/osdep.c
> index 7509c5b..9949606 100644
> --- a/osdep.c
> +++ b/osdep.c
> @@ -262,13 +262,15 @@ int qemu_pipe(int pipefd[2])
>  
>  #ifdef CONFIG_PIPE2
>      ret = pipe2(pipefd, O_CLOEXEC);
> -#else
> +    if (ret != -1 || errno != ENOSYS) {
> +        return ret;
> +    }
> +#endif
>      ret = pipe(pipefd);
>      if (ret == 0) {
>          qemu_set_cloexec(pipefd[0]);
>          qemu_set_cloexec(pipefd[1]);
>      }
> -#endif
>  
>      return ret;
>  }
> @@ -283,12 +285,14 @@ int qemu_socket(int domain, int type, int protocol)
>  
>  #ifdef SOCK_CLOEXEC
>      ret = socket(domain, type | SOCK_CLOEXEC, protocol);
> -#else
> +    if (ret != -1 || errno != EINVAL) {
> +        return ret;
> +    }
> +#endif
>      ret = socket(domain, type, protocol);
>      if (ret >= 0) {
>          qemu_set_cloexec(ret);
>      }
> -#endif
>  
>      return ret;
>  }
> @@ -302,12 +306,14 @@ int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen)
>  
>  #ifdef CONFIG_ACCEPT4
>      ret = accept4(s, addr, addrlen, SOCK_CLOEXEC);
> -#else
> +    if (ret != -1 || errno != EINVAL) {

Shouldn't this be an ENOSYS?

Kevin