Re: [meta-networking][PATCH] ebtables: make it be able to work on 64bit kernel with 32 bit userspace

[Rongqing Li <rongqing.li@windriver.com>]

On 2014年11月19日 07:12, Mark Hatle wrote:
> From: "Roy.Li" <rongqing.li@windriver.com>
>
>
> [ This patch is being sent up for Yocto Project compliance.  I'm not sure it's generally applicable. ]
>

This patch has been merged into meta-oe, but it lead to x86-64 with 32bit
user space unable to work, I am see the root cause.


-Roy

>
> Some structs, which is used to communicate between user space and kernel,
> have the alignment issue on 64bit kernel with 32 bit userspace. To fix
> this issue, ebtables redefines these struct, not use the kernel(sysroot)
> include/uapi/linux/netfilter_bridge/ebtables.h, like ebt_entry_target:
>
> The kernel's:
> struct ebt_entry_target {
>          union {
>                  char name[EBT_FUNCTION_MAXNAMELEN];
>                  struct xt_target *target;
>          } u;
>          /* size of data */
>          unsigned int target_size;
>          unsigned char data[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));
> };
>
> The ebtables:
> struct ebt_entry_target
> {
>          union {
>                  char name[EBT_FUNCTION_MAXNAMELEN];
>                  struct ebt_target *target;
>          } u;
>          /* size of data */
>          unsigned int target_size;
> |#ifdef KERNEL_64_USERSPACE_32
>          unsigned int pad;
> |#endif
>          unsigned char data[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));
> };
>
> To make it work on 64bit kernel and 32bit userspace, KERNEL_64_USERSPACE_32
> is needed to be enabled.
>
> If the MLPREFIX of package matchs "lib.?32", the 32bit multilib  package on
> 64bit kernel is being built.
>
> Signed-off-by: Roy.Li <rongqing.li@windriver.com>
> Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
> ---
>   recipes-filter/ebtables/ebtables_2.0.10-4.bb | 11 +++++++++++
>   1 file changed, 11 insertions(+)
>
> diff --git a/recipes-filter/ebtables/ebtables_2.0.10-4.bb b/recipes-filter/ebtables/ebtables_2.0.10-4.bb
> index 32cfc75..ca084e3 100644
> --- a/recipes-filter/ebtables/ebtables_2.0.10-4.bb
> +++ b/recipes-filter/ebtables/ebtables_2.0.10-4.bb
> @@ -27,6 +27,17 @@ S = "${WORKDIR}/ebtables-v${PV}"
>
>   inherit update-rc.d systemd
>
> +python __anonymous () {
> +    import re
> +
> +    multilib = d.getVar('MLPREFIX', True)
> +    if multilib:
> +        searchstr = "lib.?32"
> +        reg = re.compile(searchstr)
> +        if reg.search(multilib):
> +            d.appendVar('CFLAGS' ,' -DKERNEL_64_USERSPACE_32 -DEBT_MIN_ALIGN=8')
> +}
> +
>   EXTRA_OEMAKE = " \
>           BINDIR=${base_sbindir} \
>           MANDIR=${mandir} \
>

-- 
Best Reagrds,
Roy | RongQing Li