Hi Alejandro,
we added IFF_ECHO these days on suggestion of Dave Miller - and the
IFF_LOWER_UP/IFF_DORMANT were already there at that time.
I don't know if there ioctls are still used for retrieving these flags
as I assume this is done via netlink interface today.
At least there is enough space (in the union) in the ioctl structure for
longer data structures:
https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/if.h#L265
https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/if.h#L247
https://elixir.bootlin.com/linux/latest/source/net/core/dev_ioctl.c#L114
If you continue discussing about this topic, please remove the
Volkswagen mail addresses from Urs and me.
I'm still maintaining the CAN subsystem in the Linux kernel - but with a
private mail address.
And you should better add the netdev ML to your recipients
netdev@vger.kernel.org where all the netdev guys (including Dave Miller)
hang out.
Best,
Oliver
------------------------------------------------------------------------
*Von:* Alejandro Colomar (man-pages) <alx.manpa...@gmail.com>
*Gesendet:* Freitag, März 19, 2021 9:00 PM
*An:* Erik Flodin; mtk.manpa...@gmail.com
*Cc:* linux-...@vger.kernel.org; Stefan Rompf; David S. Miller; Fredrik
Arnerup; John Dykstra; David S. Miller; Hartkopp, Oliver, Dr. (EESC/3);
Thuermann, Urs, Dr. (K-AERD/M)
*Betreff:* Re: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS
[CC += Fredrik, John, David S., Steven, Oliver, Urs]
Hi,
On 3/17/21 3:12 PM, Erik Flodin wrote:
Hi,
The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in netdevice.7 lists
IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
ifr_flags as it is only a short and the flags start at 1<<16.
See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c>
I don't know what's the history of that.
I researched a bit, and while the struct member is indeed a 'short' [1],
the flags were added to the kernel for some reason.
I added a few people to the thread that may know better what to do.Let's
see if they can comment.
Links to relevant commits:
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c>>
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b00055aacdb172c05067612278ba27265fcd05ce
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b00055aacdb172c05067612278ba27265fcd05ce>>
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cd05acfe65ed2cf2db683fa9a6adb8d35635263b
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cd05acfe65ed2cf2db683fa9a6adb8d35635263b>>
<https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=6ecda4d14604d250d385346f4fe9de707f281759
<https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=6ecda4d14604d250d385346f4fe9de707f281759>>
Thanks,
Alex
[1]:
.../linux$ sed -n '/struct ifreq {/,/};/p' include/uapi/linux/if.h
struct ifreq {
#define IFHWADDRLEN 6
union
{
char ifrn_name[IFNAMSIZ]; /* if name,
e.g. "en0" */
} ifr_ifrn;
union {
struct sockaddr ifru_addr;
struct sockaddr ifru_dstaddr;
struct sockaddr ifru_broadaddr;
struct sockaddr ifru_netmask;
struct sockaddr ifru_hwaddr;
short ifru_flags;
int ifru_ivalue;
int ifru_mtu;
struct ifmap ifru_map;
char ifru_slave[IFNAMSIZ]; /* Just fits the size */
char ifru_newname[IFNAMSIZ];
void __user * ifru_data;
struct if_settings ifru_settings;
} ifr_ifru;
};
.../linux$ grep 'define\sifr_flags' include/uapi/linux/if.h
#define ifr_flags ifr_ifru.ifru_flags /* flags */
.../linux$
--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
<https://www.kernel.org/doc/man-pages/>
http://www.alejandro-colomar.es/ <http://www.alejandro-colomar.es/>
