On 4/21/22 07:43, Rich Felker wrote:
On Thu, Apr 21, 2022 at 08:52:59AM +0200, Geert Uytterhoeven wrote:
On Thu, Apr 21, 2022 at 1:53 AM Greg Ungerer <gerg@xxxxxxxxxxxxxx> wrote:
On 21/4/22 00:58, Eric W. Biederman wrote:
In a recent discussion[1] it was reported that the binfmt_flat library
support was only ever used on m68k and even on m68k has not been used
in a very long time.
The structure of binfmt_flat is different from all of the other binfmt
implementations becasue of this shared library support and it made
life and code review more effort when I refactored the code in fs/exec.c.
Since in practice the code is dead remove the binfmt_flat shared libarary
support and make maintenance of the code easier.
[1] https://lkml.kernel.org/r/81788b56-5b15-7308-38c7-c7f2502c4e15@xxxxxxxxxxxxxx
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
Can the binfmt_flat folks please verify that the shared library support
really isn't used?
I can definitely confirm I don't use it on m68k. And I don't know of
anyone that has used it in many years.
Was binfmt_flat being enabled on arm and sh the mistake it looks like?
I think the question was intended to be
Was *binfmt_flat_shared_flat* being enabled on arm and sh the
mistake it looks like?
Early in my work on j2, I tried to research the history of shared flat
support on sh, and it turned out the mainline tooling never even
supported it, and the out-of-line tooling I eventually found was using
all sorts of wrong conditionals for how it did the linking and elf2flt
conversion, e.g. mere presence of any PIC-like relocation in any file
made it assume the whole program was PIC-compatible. There's no way
that stuf was ever used in any meaningful way. It just didn't work.
Quickly dropped that and got plain ELF (no shared text/xip, but no
worse than the existing flat support) working, and soon after, FDPIC.
The whole binfmt_flat ecosystem is a mess with no good reason to
exist.
FYI when I had to come up to speed on this in 2014 I did a writeup on my own
research:
https://landley.net/notes-2014.html#07-12-2014
The lack of a canonical "upstream" elf2flt repository was probably the biggest
problem at the time.
(There's a reason I grabbed fdpic hard and tried to make that work everywhere.)
Rich
Rob
