Subject: Re: [PATCH v3 0/4] xfrm: add x86 CONFIG_COMPAT support

From: Patrick McHardy <[email-masked]>
Date: Thu, 08 Apr 2010 13:24:17 +0200

David Miller wrote:
> From: Patrick McHardy <[email-masked]>
> Date: Thu, 08 Apr 2010 11:44:43 +0200
> 
>> Either the kernel or the userspace programs have to be updated
>> either way.
> 
> The only case in which we only have to change one side is if we add
> the full set of compat support to the kernel.
> 
> If we take any other option (new XFRM numbers and new datastructures,
> or only convert sendmsg() to do compat translations), it requires both
> the kernel and userspace to change.

You're right of course.

> And the currently existing 32-bit binaries don't work on 64-bit
> kernels because of something that cannot be classified any other way
> than as being a kernel bug.

Agreed, but since its not a new bug, I think we have some flexibility
in how to fix it. In the wireless case we had no real choice but to
add the COMPAT_NETLINK thing, but its a bit sad to add more of this
crap to netlink.

Anyways, I guess there's no reason why we couldn't do both and
transistion to a fixed API in the long term.