Re: arch/mips (and arch/alpha) pmap.c dependency on SYSVSHM

[Paul Goyette <paul%vps1.whooppee.com@localhost>]

On Thu, 5 Nov 2015, Paul Goyette wrote:

> Following up on my earlier modularization of the SYSV IPC code, I have
> discovered that mips's pmap.c includes some SYSVSHM size in the calcs
> for the system map sizes.  At line 516 in arch/mips/mips/pmap.c we have
>
> #ifdef SYSVSHM
>        Sysmapsize += shminfo.shmall;
> #endif
>
> In arch/alpha/alpha/pmap.c we have at line 781
>
> #ifdef SYSVSHM
>        lev3mapsize += shminfo.shmall;
> #endif

We also have the following code in arch/powerpc/booke/booke_pmap.c at
line 199

#ifdef SYSVSHM
            + NBPG * shminfo.shmall
#endif


> Since SYSVSHM could be loaded as a module, rather than being built-in
> to the kernel, would it be reasonable to remove these #ifdef's and
> thus always include the increment to the map sizes?
>
> It seems that noone is currently using modular sysv_ipc on either mips
> or alpha, since otherwize I would have expected some fallout from an
> incorrect sizing of the system map.  Including the above code
> unconditionally should not have a significant impact on kernel size
> even for those kernels that don't include the SYSVSHM code.


I propose that all three of these "system size" decisions be made
unconditional, and assume the SYSVSHM either exists, or can exist
via loading of a module.


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