Changes to kextsymboltool for Big Sur?

Question

Created Jun ’20

Replies 2

Boosts 0

Participants 2

We use kextsymboltool when compiling our kext, but kexts will not load on Big Sur, generally it simply claims it can not find the Plugins/module.kext, or if I try to codesign Plugins/module.kext I get;
... because file does not have a __LINKEDIT segment

I'm guessing there has been some slight changes to make kextsymbtoltool.c up to date, anything I can handle now, or must I wait for XNU source?

Boost

Answer 1

Systems Engineer OP

Apple

Jun ’20

In Big Sur we have made significant changes to the way kexts are linked and loaded on the system, however the compilation of your kext should work as it has in previous releases.

How are you using kextsymboltool in your compilation?

1

Answer 2

lundman OP

Jun ’20

Ok well, you may not want to see this;

So there are a bunch of functions we desperately need to call to be able to function (38 to date), so we produce a "Codeless Kernel Extension" to help us link, like;

Code Block  $(NM) -gj $(MACH_KERNEL) > allsymbols
./kextsymboltool -arch x86_64 -import allsymbols -export zfs.exports -output kernelexports_64
 lipo -create kernelexports_32 kernelexports_64 -output kernelexports
 cp kernelexports zfs.kext/Contents/Plugins/KernelExports.kext/KernelExports

then tie the main kext to depend on it, and voila. Alas, some changes to "kextsymboltool" must have happened for BigSur, so the version in Catalina no longer produces something that BigSur will load. I guess I was hoping for "kextsymboltool.c", but that's probably too soon, so maybe a binary of "kextsymboltool".

Ultimately, we'd love to get rid of the 38 items in zfs.exports file, but not found solutions for the issues they solve - but that is a whole other thing, and will probably become moot when kexts are removed entirely.

0