Re: [PATCH] sparc64 compatibility netfilter patches

[Laszlo Valko <valko@linux.karinthy.hu>]

On Wed, Jan 01, 2003 at 10:22:23PM -0800, David S. Miller wrote:
> 
> The hack for building the tools is wrong, there are 64-bit
> compilers and userspace available.

I totally agree that this hack is the wrong way to do it.
It will definitely not work with 64-bit userspace.

> The real fix for that (for when your tools are 32-bit) is
> to run "sparc32 /bin/sh" and compile in that environment.

I don't see how that would solve our problem. It will probably
produce working code with 64-bit userspace, but not in the mixed
bit-length case.

Actually, the hack with KERNEL_64_USERSPACE_32 in the tools had
existed before I even looked at the code. It was too tempting to
extend it to my case even tough I know it's not good :)


There are basically two "good" and a "worse" solution:

1) make the kernel interface saner by excluding longs and pointers
   altogether, and cleaning it up by separating "interface" and
   "kernel internal" variables/structures (complicated, introducing
   incompatible API changes),

2) do kernel side 32-64 bit conversions (ugly, big performance
   penalty, looks like a big hack, difficult to maintain),

3) make a similar hack, like there currently is, but with correct
   userspace-kernelspace bit-length checking, and do the magic in
   the tools (even uglier, but no performance penalty and easier to
   maintain).

None of them are simple.

In the long run, I vote for the first one.
If I have a spare week, I might as well try to "sink" into the
netfilter code, and implement something...

> I'll be looking at the kernel side patch next, it should be
> ok.

Thanks.

Laszlo
e-mail: <valko@linux.karinthy.hu>