[U-Boot] [PATCH 2/2] [NEXT] arm926ejs: reduce code size with -msingle-pic-base

Rogan Dawes
2010-09-24T16:45:20Z

On 2010/09/24 7:47 AM, Albert ARIBAUD wrote:

> On a side note, I do not know of a clear general definition of
> 'bisectability', which means I could break it yet again unkonwingly. Can
> you (or anyone, actually :) ) point me to a, or even the, standard
> definition of 'bisectable' and, if that has a specific meaning, of
> 'fully bisectable'?

Not sure if there is an agreed definition, but the main idea behind
bisection stems from the "git bisect" tool, which allows you to mark one
commit as "known good", and another as "known bad", and then calculates
a commit in the middle to be tested for "goodness" or "badness". As
commits are marked "good" or "bad", the tool halves (bisects) the range
of commits until the single commit that introduced the breakage can be
identified.

Of course, for the bisection process to be able to work, all points
along the path must a) compile and b) be able to be tested for the breakage.

So, a fully bisectable patch series would maintain the above properties,
for all boards.

This is one of the reasons that Linus likes to have code used as it is
introduced, rather than building up a whole lot of unused
infrastructure, only to activate it with a final commit. The bisection
would then point to the final commit as the culprit, when the true
failure may have been introduced by one of the preceding commits.

That's "as I understand it", of course.

Rogan