John David Anglin <dave.anglin@xxxxxxxx> wrote:
On 6-Apr-13, at 6:52 AM, James Bottomley wrote:
On Sat, 2013-04-06 at 15:22 +1030, Rusty Russell wrote:"AnThe problem is our assumption that section names be unique. This
assumption is wrong. The ELF spec says (version 1.1 page 1-15):
object file may have more than one section with the same name."
We need
to fix the kernel not to rely on a bogus assumption ... but we had
no
idea how to do that in a way that preserved the backwards
compatibility
of sections subdirectory.
I admit that 35dead4235e2b67da7275b4122fed37099c2f462 is a hack,
but now
the problem has got attention, can we fix it properly?
Yep. The original patch didn't go through me, or we would have had
this
discussion back then...
The use of section names in sysfs goes back to one Mr. Corbet. Why
shoulddid
he do it that way? Because gdb's add-symbol-file makes the same
assumption. So if we fixed the sysfs somehow, it still wouldn't be
useful, since there's no way to tell gdb :(
The real answer don't use -ffunction-sections on modules: probably
not
as important as the rest of the kernel. And the new shiny is
-flto anyway.
And that leaves us with a PA-RISC specific issue, for which wesinglemove the fix to PA-RISC.
Thoughts?
Well, we don't have much of a choice. Our ELF stub jump on 32 bits
is a
PCREL17. That means once a module size is over 128k there's a
chance we
might not be able to link it because the jump is too big for the
instruction. IPV6 is one such big module today, but I'm sure there
are
others. The only way I know to fix this is to allow the linker to
insert stubs between functions, so we only fail at linking if a
function is >128k big. The way to do this is -ffunction-sections,way
unless there's something else we could do (all we really need is a
to ensure we can insert ELF stubs every 128k).
There is now a config work around for this. See:
http://www.spinics.net/lists/linux-parisc/msg04521.html
The longcalls config option only works on pa2 doesn't it? Although we could just deprecate pa1.