Re: enabling libgcc for 64-bit divisions, was Re: PROBLEM: XFS on ARM corruption 'Structure needs cleaning'

From: Linus Torvalds
Date: Wed Aug 12 2015 - 18:36:20 EST

On Wed, Aug 12, 2015 at 3:20 PM, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
> Does your objection still apply if we supplied our own implementations of a
> handful of libgcc helpers?

We already do that.

Several architectures actually implement _udivdi3.

However, do_div() is actually the much simpler/better interface.

I don't think we have a single case in the kernel where we really want
the full 64/64 division, and the 64/32->64 case really is
fundamentally simpler.

This whole "do_div is so complicated" thing is just BS.

The thing that triggered Christoph to ask was a bug in the
implementation of that *simpler* interface. What makes you think that
making people implement _udivdi3 would magically avoid all such bugs?

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