[PATCH RFC] ARM: option for loading modules into vmalloc area

Nicolas Pitre nicolas.pitre at linaro.org
Wed Nov 19 09:12:18 PST 2014

On Wed, 19 Nov 2014, Russell King - ARM Linux wrote:

> On Wed, Nov 19, 2014 at 11:57:15AM -0500, Nicolas Pitre wrote:
> > On Wed, 19 Nov 2014, Russell King - ARM Linux wrote:
> > > I don't think I ever did, because its pretty much impossible to do as I
> > > explained in a follow up to this thread.
> > > 
> > > We _used_ to do this with the userspace insmod methods, but since we got
> > > this kernel-side linker, it's been pretty much impossible to do without
> > > rewriting the module code.  That's not going to happen on account of one
> > > quirky architecture which Linus doesn't particularly like.
> > 
> > Still... We could try adding a hook in the generic module linker code 
> > for a pre-relocation pass.  Maybe only ARM would use it, but if the need 
> > to load big modules is real then I imagine Linus could be amenable to a 
> > compromise.
> So, how big a table would you allocate for the trampolines, based upon
> not knowing anything about the module being loaded?  4K?  8K?  64K?

The idea of a pre-relocation pass is to determine that.  That could be 
something similar to calling apply_relocate() twice: once to determine 
the number of trampoline entries, and a second time to perform the 
actual relocation.


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