RPI3 - clang 3.9.0 issues

[Shawn Webb]

Hey All,

I'm submitting this report to this list as directed by Ed Maste.

The Raspberry Pi 3 is an ARMv8 SoC dev board. Within the last week,
FreeBSD added basic initial support for it. We don't currently have a
linker in HEAD for the arm64/aarch64 platform. The
projects/clang390-import branch contains lld, though, which supports
arm64/aarch64.

Over the past few days, I've been working on testing clang 3.9.0 and lld
on the RPI3. I've jotted down a few issues in FreeBSD's wiki:

https://wiki.freebsd.org/arm64/rpi3

Mainly:

low-level code like bootloaders (boot1.efi and loader.efi) do NOT work
with projects/clang390-import. When I use boot1.efi and loader.efi
compiled with HEAD (clang 3.8), they work.

When the kernel is compiled with clang 3.9.0, it seems to freeze after
being loaded by the clang 3.8 boot1.efi/loader.efi. I'm unsure if it's
actually frozen or if simply nothing is being outputted to the console.
Either way, I don't see console messages and the RPI3 _appears_ frozen.

I'm tracking down a potential issue with jemalloc compiled with clang
3.9.0, but I need to verify that the issue exists in vanilla FreeBSD in
addition to HardenedBSD. Most of my testing has been done with
HardenedBSD to-date.

If I find more issues or find the causes of the ones I've already
documented, I'll be sure to not only update the wiki, but update this
email thread as well.

If there's anything anyone would like me to try, please let me know.

Thanks,

-- 
Shawn Webb
Cofounder and Security Engineer
HardenedBSD

GPG Key ID:          0x6A84658F52456EEE
GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89  3D9E 6A84 658F 5245 6EEE
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