On Thu, Feb 10, 2011 at 7:11 PM, Russell King - ARM Linux
[off-list ref] wrote:

On Thu, Feb 10, 2011 at 06:29:41PM +0000, Dave Martin wrote:

quoted

On Thu, Feb 10, 2011 at 2:46 PM, Russell King - ARM Linux
[off-list ref] wrote:

quoted

On Thu, Feb 10, 2011 at 02:13:13PM +0000, Dave Martin wrote:

quoted

Note that this tree contains some extra patches (though I believe
nothing is there which should cause the problem), and does not contain
everything from rmk/devel -- so it's possible this has been fixed in
the meantime or no longer occurs for some other reason...

No need - I now have some modules which contain SMP alternatives, so we
do need to fix the module loader for this, and keep the SMP alternatives
replacement code around. ?It's not worth eliminating the code as if we
include an informative printk() to say why we're refusing to load the
module, the string would be larger than the code it eliminates. ?So, I
think we need to merge the patch below to avoid run-time problems.

I thought the problem was not caused by removal of the fixup code, but
rather by the removal of code referenced by fixups?

It is. ?But:

arm-linux-objdump -h sound/core/snd-timer.ko

sound/core/snd-timer.ko: ? ? file format elf32-littlearm

Sections:
Idx Name ? ? ? ? ?Size ? ? ?VMA ? ? ? LMA ? ? ? File off ?Algn
?0 .text ? ? ? ? 00002f34 ?00000000 ?00000000 ?00000034 ?2**2
? ? ? ? ? ? ? ? ?CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
?1 .exit.text ? ?00000070 ?00000000 ?00000000 ?00002f68 ?2**2
? ? ? ? ? ? ? ? ?CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
?2 .init.text ? ?000001b4 ?00000000 ?00000000 ?00002fd8 ?2**2
? ? ? ? ? ? ? ? ?CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
?3 .rodata ? ? ? 000000bc ?00000000 ?00000000 ?0000318c ?2**2
? ? ? ? ? ? ? ? ?CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
?4 .rodata.str1.1 00000156 ?00000000 ?00000000 ?00003248 ?2**0
? ? ? ? ? ? ? ? ?CONTENTS, ALLOC, LOAD, READONLY, DATA
?5 .alt.smp.init 00000088 ?00000000 ?00000000 ?0000339e ?2**0
? ? ? ? ? ? ? ? ?CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
...

Here we have a module which contains the spin_unlock assembly, which
contains the SMP alternatives. ?If we insert that into a kernel also
built with SMP alternatives support, but which is running on a UP
system, we need to run these fixups as well when the module is loaded.

Agreed -- actually, I suspected we might need to support this.  But I
don't think solving this problem (= keeping the fixup implementation
in memory and enhancing the module loader) solved the
fixups-referencing-sections-discarded-from-vmlinux problem.  These
seem to be two separate issues.  I am filing to understand something?

Cheers
---Dave