Re: [PATCH 4/7] x86/vm86: Move vm86 fields out of thread_struct

From: Linus Torvalds
Date: Wed Aug 05 2015 - 04:53:29 EST


On Wed, Aug 5, 2015 at 10:48 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>>
>> Some of these field names are visible to userspace and can't change.
>
> That's a misconception: bits in the uapi headers can be renamed just fine.

I disagree. If it causes pain for user space, we just shouldn't do it.
Some people copy the headers (preferred), others include the kernel
header directory with a include path or a symlink, and it's damn
painful if we start changing things that user space depends on.

I'd say that it's like the ABI - if people don't really notice, you
can do it, but if it breaks the build of a user app, we should be very
very careful. The breakage is often hard to fix because of nasty
versioning issues..

Our goal in life really is "don't screw up user space".

Linus
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