libgtop is the top blocker on https://wiki.freebsd.org/PortsBrokenWithSbrk. It's broken because an example uses some sbrk(0) calls as an unreliable and non-portable way to demonstrate memory utilization. The attached patch removes them as they are pointless and likely wrong in practice. This should allow libgtop to build and arm64 and riscv.
Created attachment 185725 [details] patch
A commit references this bug: Author: kwm Date: Mon Sep 25 19:27:05 UTC 2017 New revision: 450629 URL: https://svnweb.freebsd.org/changeset/ports/450629 Log: Allow to build on arm64 and riscv by removing the usage of sbrk(2), which doesn't exist on arm64 and riscv. PR: 221751 Submitted by: brooks@ Changes: head/devel/libgtop/files/patch-examples_mountlist.c