5 Nov
2024
5 Nov
'24
9:14 a.m.
The bmap implementations I saw were bit for bit identical, same code, same
variables, same style, same indentation. I'm 100% sure they were not
independent. 100% sure.
I've traced that code through all the Bell Labs stuff to BSD. The idea
that BSD redid this code the same way, in my mind, is a bridge too far.
bmap() knows about how stuff is laid out on disk, knows about how stuff
works in the inode (think indirect blocks and double indirect blocks),
there is _no_ _way_ BSD wrote the same code independently. No f-ing
way. They just took it.
I know we all want to think all the Bell Labs code is free or has been
reimplemented and it's all good, we're clean. We're not.
It doesn't matter at this point but it matters to me that we are honest
about how we got here.
On Mon, Nov 04, 2024 at 05:32:19PM -0800, ron minnich wrote:
I had people relate to me, at least once, cases of
utterly independent
implementations of a function that were byte for byte the same, as found in
one court case a friend of mine (now deceased) got pulled into. He had to
prove he'd written his code from scratch. But these were pretty simple
functions. I don't know if bmap qualifies ...
How could this happen? I don't know, but the court case that long predated
SCO. The only conclusion I can reach
is that when enough techniques, ideas, mailling lists, discussions, and
documents become part of a shared culture, the code which
people create might be the same. A weird parallel evolution of code.
On Mon, Nov 4, 2024 at 5:09???PM Larry McVoy <lm(a)mcvoy.com> wrote:
> The thing I never got a reasonable answer to was I found code in BSD that
> was identical to code going back to at least V7. Find bmap() in the UFS
> code and then find the same in V7. I might be wrong about V7, might be
> 32V, might be V6. I don't think it matters, it's the same in all of
them.
>
> bmap() is the code that maps a logical block to a phsyical block,
> I'm quite familiar with it because I rewrote it to bmap_write() and
> bmap_read() as part of making UFS do extents:
>
> http://mcvoy.com/lm/papers/SunOS.ufs_clustering.pdf
>
> When all the lawsuits were going on, since I knew that code really well,
> I went off and looked and the BSD code at that time had bit for bit
> identical bmap() implementations.
>
> I never understood why BSD could claim they rewrote everything when they
> clearly had not rewritten that.
>
> I've raised this question before and I just went and looked, bmap() has
> changed. I'm pretty sure I have Kirk's BSD source releases, if I do,
> I'm 100% sure I can back up what I'm saying. Not sure I care enough to
> do so, it's all water under the bridge at this point.
> --
> ---
> Larry McVoy Retired to fishing
> http://www.mcvoy.com/lm/boat
>
--
---
Larry McVoy Retired to fishing http://www.mcvoy.com/lm/boat