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Formalize the use of linker scripts for kernel modules.
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Authored by markj on Thu, Oct 3, 4:05 PM.

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Summary

Automatically use ldscript.kmod.${MACHINE_CPUARCH} if it exists.
We already have an i386-specific linker script; rename it accordingly.
I plan to add an amd64 linker script to insert padding after .text
and .rodata*, so that permission boundaries are page-aligned. (It turns
out that my plan to use DSOs on amd64 will not work because of issues
that arise when combining -mcmodel=kernel and -fPIC.)

Note that the linker script is applied during the partial link. For
amd64 (which uses .o's), this is also the final link. I think this is
probably fine, though maybe it will be useful someday to be able to
script the final link instead.

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rS FreeBSD src repository
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Event Timeline

markj created this revision.Thu, Oct 3, 4:05 PM
kib accepted this revision.Thu, Oct 3, 6:19 PM
This revision is now accepted and ready to land.Thu, Oct 3, 6:19 PM
imp added inline comments.Thu, Oct 3, 6:21 PM
sys/conf/kmod.mk
252 ↗(On Diff #62875)

So this is 'mips' for all mips things and 'powerpc' for all powerpc things.
History has shown that we really want to have both the ability to check MACHINE_ARCH as well as the more generic MACHINE_CPUARCH.
Would it be possible to update to do that?

jhb added inline comments.Thu, Oct 3, 6:36 PM
sys/conf/kmod.mk
252 ↗(On Diff #62875)

We can probably wait to fix that until an actual use case turns up. My inclination would be to actually use MACHINE_ARCH instead of MACHINE_CPUARCH for now (a no-op on i386 and amd64), though it really doesn't matter. I'm somewhat surprised the original code used CPUARCH for this.

markj updated this revision to Diff 62908.Fri, Oct 4, 5:18 PM

Use MACHINE_ARCH instead of MACHINE_CPUARCH.

This revision now requires review to proceed.Fri, Oct 4, 5:18 PM
imp accepted this revision.Fri, Oct 4, 5:26 PM

I'm cool with jhb's reasoning, so this looks ready to land.

This revision is now accepted and ready to land.Fri, Oct 4, 5:26 PM
This revision was automatically updated to reflect the committed changes.