Re: Update headers for Linux 3.15

[Will Newton <will dot newton at linaro dot org>]

On 17 June 2014 16:53, Joseph S. Myers <joseph@codesourcery.com> wrote:
> This patch updates glibc headers for changes / new definitions in
> Linux 3.15.  In the course of my review I noticed that
> IPV6_PMTUDISC_INTERFACE was absent from glibc despite the inclusion of
> IP_PMTUDISC_INTERFACE; I added it along with IP_PMTUDISC_OMIT and
> IPV6_PMTUDISC_OMIT.  I did not add FALLOC_FL_NO_HIDE_STALE given the
> kernel header comment that it is reserved.
>
> Review of this patch should probably include the question of whether
> the definitions added are indeed all wanted in glibc's headers, and
> whether anything else from 3.15 requires glibc changes (although the
> latter should not need to block the patch).
>
> Deliberately omitted from this patch:
>
> * MicroBlaze kernel-features.h changes for new syscalls (untested
>   patch to be sent separately).
>
> * ARM HWCAP2 - since proper support should include dl-procinfo changes
>   (like the powerpc dl-procinfo), not just bits/hwcap.h, this is
>   probably best done by someone with access to hardware on which the
>   new bits are set.

QEMU implements all of these extensions AFAIK.

> * MIPS sigcontext - as I noted in
>   <https://sourceware.org/ml/libc-alpha/2014-06/msg00411.html>, I
>   think the changes are fundamentally flawed and should best be
>   reverted until a more compatible solution can be produced (and then
>   any glibc changes would best be done with access to MSA hardware).
>
> * F_OFD_* (patch has already been posted
>   <https://sourceware.org/ml/libc-alpha/2014-06/msg00126.html> but may
>   need review).
>
> * IFF_ECHO for net/if.h (previous values IFF_LOWER_UP and IFF_DORMANT
>   also omitted and I'm presuming the omission of values that don't fit
>   in the "short" flags field is deliberate).
>
> * renameat2 - this relates to the general question of when glibc
>   should provide bindings to Linux kernel syscalls, which requires
>   someone to take the lead on producing an analysis with reference to
>   the various previous threads on this subject, seeking consensus on
>   principles for when to provide such bindings, and then adding
>   bindings for whatever syscalls meet the principles but don't
>   currently have them.
>
> Tested x86_64.
>
> 2014-06-17  Joseph Myers  <joseph@codesourcery.com>
>
>         * sysdeps/unix/sysv/linux/bits/fcntl-linux.h [__USE_GNU]
>         (FALLOC_FL_COLLAPSE_RANGE): New macro.
>         [__USE_GNU] (FALLOC_FL_ZERO_RANGE): Likewise.
>         * sysdeps/unix/sysv/linux/bits/in.h (IP_PMTUDISC_OMIT): Likewise.
>         (IPV6_PMTUDISC_INTERFACE): Likewise.
>         (IPV6_PMTUDISC_OMIT): Likewise.

These all look like reasonable additions to me.

> diff --git a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> index 915eb3e..527eb5c 100644
> --- a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> +++ b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> @@ -305,6 +305,11 @@ struct f_owner_ex
>                                              even if offset + len is
>                                              greater than file size.  */
>  # define FALLOC_FL_PUNCH_HOLE          2 /* Create a hole in the file.  */
> +# define FALLOC_FL_COLLAPSE_RANGE      8 /* Remove a range of a file
> +                                            without leaving a
> +                                            hole.  */
> +# define FALLOC_FL_ZERO_RANGE          16 /* Convert a range of a
> +                                             file to zeros.  */
>
>
>  /* File handle structure.  */
> diff --git a/sysdeps/unix/sysv/linux/bits/in.h b/sysdeps/unix/sysv/linux/bits/in.h
> index f5b02dd..1331e1b 100644
> --- a/sysdeps/unix/sysv/linux/bits/in.h
> +++ b/sysdeps/unix/sysv/linux/bits/in.h
> @@ -101,6 +101,8 @@
>     Also incoming ICMP frag_needed notifications will be ignored on
>     this socket to prevent accepting spoofed ones.  */
>  #define IP_PMTUDISC_INTERFACE           4
> +/* Like IP_PMTUDISC_INTERFACE but allow packets to be fragmented.  */
> +#define IP_PMTUDISC_OMIT               5
>
>  #define IP_MULTICAST_IF                        32
>  #define IP_MULTICAST_TTL               33
> @@ -214,6 +216,8 @@ struct in_pktinfo
>  #define IPV6_PMTUDISC_WANT     1       /* Use per route hints.  */
>  #define IPV6_PMTUDISC_DO       2       /* Always DF.  */
>  #define IPV6_PMTUDISC_PROBE    3       /* Ignore dst pmtu.  */
> +#define IPV6_PMTUDISC_INTERFACE        4       /* See IP_PMTUDISC_INTERFACE.  */
> +#define IPV6_PMTUDISC_OMIT     5       /* See IP_PMTUDISC_OMIT.  */
>
>  /* Socket level values for IPv6.  */
>  #define SOL_IPV6        41
>
> --
> Joseph S. Myers
> joseph@codesourcery.com



-- 
Will Newton
Toolchain Working Group, Linaro