RE: Re: [PATCH 1/1] arm/module: maximum utilization of module area.

[Nicolas Pitre]

On Mon, 12 Dec 2016, Vaneet Narang wrote:

> Hi,
> 
> >A PC24 relocation has a range of +/-32MB.  This means that where-ever
> >the module is placed, it must be capable of reaching any function
> >within the kernel text, which may itself be quite large (eg, 8MB, or
> >possibly larger).  The module area exists to allow modules to be
> >located in an area where PC24 relocations are able to reach all of the
> >kernel text on sensibly configured kernels, thereby allowing for
> >optimal performance.
> >
> >If you wish to load large modules, then enable ARM_MODULE_PLTS, which
> >will use the less efficient PLT method (which is basically an indirect
> >function call) for relocations that PC24 can't handle, and will allow
> >the module to be loaded into the vmalloc area.
> >
> >Growing the module area so that smaller modules also get penalised by
> >the PLT indirection is not sane.
> 
> This is exactly what i am saying. These changes are useful to accomdate
> 22MB modules without enabling ARM_MODULE_PLTS. 

I think you need to figure out why you need such a huge module in the 
first place.  That is very uncommon indeed.


Nicolas