[ovs-dev] [PATCH] FAQ: Explain what to do when building against a too-new kernel.

[Gurucharan Shetty]

On Thu, Apr 24, 2014 at 1:31 PM, Ben Pfaff <blp at nicira.com> wrote:
> Also add references to this FAQ from INSTALL and configure.
>
> Signed-off-by: Ben Pfaff <blp at nicira.com>
Acked-by: Gurucharan Shetty <gshetty at nicira.com>


> ---
>  FAQ          |   35 ++++++++++++++++++++++++++---------
>  INSTALL      |    8 ++++----
>  acinclude.m4 |    2 +-
>  3 files changed, 31 insertions(+), 14 deletions(-)
>
> diff --git a/FAQ b/FAQ
> index 6b4be43..c43b0c8 100644
> --- a/FAQ
> +++ b/FAQ
> @@ -158,18 +158,22 @@ A: The following table lists the Linux kernel versions against which the
>     It should build against almost any kernel, certainly against 2.6.32
>     and later.
>
> -Q: What Linux kernel versions does IPFIX flow monitoring work with?
> +Q: I get an error like this when I configure Open vSwitch:
>
> -A: IPFIX flow monitoring requires the Linux kernel module from Open
> -   vSwitch version 1.10.90 or later.
> +       configure: error: Linux kernel in <dir> is version <x>, but
> +       version newer than <y> is not supported (please refer to the
> +       FAQ for advice)
>
> -Q: Should userspace or kernel be upgraded first to minimize downtime?
> +   What should I do?
>
> -   In general, the Open vSwitch userspace should be used with the
> -   kernel version included in the same release or with the version
> -   from upstream Linux.  However, when upgrading between two releases
> -   of Open vSwitch it is best to migrate userspace first to reduce
> -   the possibility of incompatibilities.
> +A: If there is a newer version of Open vSwitch, consider building that
> +   one, because it may support the kernel that you are building
> +   against.  (To find out, consult the table in the previous answer.)
> +
> +   Otherwise, use the Linux kernel module supplied with the kernel
> +   that you are using.  All versions of Open vSwitch userspace are
> +   compatible with all versions of the Open vSwitch kernel module, so
> +   this will also work.  See also the following question.
>
>  Q: What features are not available in the Open vSwitch kernel datapath
>     that ships as part of the upstream Linux kernel?
> @@ -193,6 +197,19 @@ A: Tunnel virtual ports are not supported, as described in the
>     actions.  On Linux kernels before 2.6.39, maximum-sized VLAN packets
>     may not be transmitted.
>
> +Q: What Linux kernel versions does IPFIX flow monitoring work with?
> +
> +A: IPFIX flow monitoring requires the Linux kernel module from Open
> +   vSwitch version 1.10.90 or later.
> +
> +Q: Should userspace or kernel be upgraded first to minimize downtime?
> +
> +   In general, the Open vSwitch userspace should be used with the
> +   kernel version included in the same release or with the version
> +   from upstream Linux.  However, when upgrading between two releases
> +   of Open vSwitch it is best to migrate userspace first to reduce
> +   the possibility of incompatibilities.
> +
>  Q: What happened to the bridge compatibility feature?
>
>  A: Bridge compatibility was a feature of Open vSwitch 1.9 and earlier.
> diff --git a/INSTALL b/INSTALL
> index f43c65b..71ce963 100644
> --- a/INSTALL
> +++ b/INSTALL
> @@ -164,10 +164,6 @@ Prerequisites section, follow the procedure below to build.
>     To use a specific C compiler for compiling Open vSwitch user
>     programs, also specify it on the configure command line, like so:
>
> -      % ./configure CC=gcc-4.2
> -
> -   To use 'clang' compiler:
> -
>        % ./configure CC=clang
>
>     To build the Linux kernel module, so that you can run the
> @@ -177,6 +173,10 @@ Prerequisites section, follow the procedure below to build.
>
>        % ./configure --with-linux=/lib/modules/`uname -r`/build
>
> +   If --with-linux requests building for an unsupported version of
> +   Linux, then "configure" will fail with an error message.  Please
> +   refer to the FAQ for advice in that case.
> +
>     If you wish to build the kernel module for an architecture other
>     than the architecture of the machine used for the build, you may
>     specify the kernel architecture string using the KARCH variable
> diff --git a/acinclude.m4 b/acinclude.m4
> index 4269620..e6bed37 100644
> --- a/acinclude.m4
> +++ b/acinclude.m4
> @@ -137,7 +137,7 @@ AC_DEFUN([OVS_CHECK_LINUX], [
>         if test "$version" = 3 && test "$patchlevel" -le 13; then
>            : # Linux 3.x
>         else
> -         AC_ERROR([Linux kernel in $KBUILD is version $kversion, but version newer than 3.13.x is not supported])
> +         AC_ERROR([Linux kernel in $KBUILD is version $kversion, but version newer than 3.13.x is not supported (please refer to the FAQ for advice)])
>         fi
>      else
>         if test "$version" -le 1 || test "$patchlevel" -le 5 || test "$sublevel" -le 31; then
> --
> 1.7.10.4
>
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