[dpdk-dev] [PATCH v2] drivers/net:new PMD using tun/tap host interface

[Wiles, Keith]

Regards,
Keith

> On Sep 20, 2016, at 12:05 AM, Yuanhan Liu <yuanhan.liu at linux.intel.com> wrote:
> 
> [ just got few more comments after some fiddling with the build issue ]
> 
> On Fri, Sep 16, 2016 at 11:22:13AM -0500, Keith Wiles wrote:
>> diff --git a/drivers/net/tap/Makefile b/drivers/net/tap/Makefile
>> new file mode 100644
>> index 0000000..442a2fe
>> --- /dev/null
>> +++ b/drivers/net/tap/Makefile
>> @@ -0,0 +1,60 @@
>> +#   BSD LICENSE
>> +#
>> +#   Copyright(c) 2014 John W. Linville <linville at redhat.com>
>> +#   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
>> +#   Copyright(c) 2014 6WIND S.A.
> 
> Just wondering, is it on purpose, or just yet another copy-paste error?

Yes, I will send another patch to fix this one.

> 
>> +#include <arpa/inet.h>
>> +#include <net/if.h>
>> +#ifdef __linux__
> 
> So, you meant to add other OS support, say BSD?

I did not mean to support BSD, just Linux and I will remove the ifdef to reflect it. If you look at the configuration file I only added it to the common_linux file and not BSD.

The concern I am having is on my standard Ubuntu 16.04 system these errors do not appear. I would like to understand why they appeared on your system. The ifdef __linux__ must be enabled as the defines in the linux/if_tun.h file do not give an error. I did play with the headers already and removed the ifdef, but as I could not reproduce your build failure it did not trigger anything new.

I will look at it some more, but it does not make sense and I do want to make sure it works.

> 
>> +#include <linux/if.h>
>> +#include <linux/if_tun.h>
>> +#include <linux/if_ether.h>
>> +#else
>> +#include <netinet/if_ether.h>
>> +#endif
>> +#include <fcntl.h>
>> +
>> +#include <poll.h>
>> +
>> +/* Linux based path to the TUN device */
>> +#define TUN_TAP_DEV_PATH        "/dev/net/tun"
> 
> However, you hardcoded a linux only path here. While checking the code
> from qemu, I saw that the path is actually different from different UNIX
> variants, even for FreeBSD and NetBSD.

I only assumed this to work for Linux and not FreeBSD/NetBSD as the handling of the opens on the tun device are different then linux. I also only added it to the common_linux configuration file.

> 
>    [yliu at yliu-dev ~/qemu]$ grep -E "/dev/.*(tap|tun)" net/tap*.c
>    net/tap-bsd.c:            snprintf(dname, sizeof dname, "/dev/tun%d", i);
>    net/tap-bsd.c:            snprintf(dname, sizeof dname, "/dev/tap%d", i);
>    net/tap-bsd.c:#define PATH_NET_TAP "/dev/tap"
>    net/tap-linux.c:#define PATH_NET_TUN "/dev/net/tun"
>    net/tap-solaris.c:    TFR(tap_fd = open("/dev/tap", O_RDWR, 0));
>    ...
> 
> 	--yliu