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

From: Russell King - ARM Linux
Date: Mon Dec 12 2016 - 07:57:13 EST

On Mon, Dec 12, 2016 at 11:22:30AM +0000, 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.

Obviously I wasn't clear enough.

No, I do not like your change for the reasons given above. I'm not going
to accept it.

If you want to use 22MB modules, enable ARM_MODULE_PLTS.

Thank you.

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