In reply to @SeTSeR:matrix.org
Hello, I'm trying to build NixOS image for Starfive VisionFive 2 using this repo:
https://github.com/NickCao/nixos-riscv
I was able to build vanilla image, but the problems arose when I tried to add `xrdp` to it. Compilation of xrdp began to fail with bizarre errors on `pkg-config` missing. I looked into derivation for xrdp and found out that for some reason that `xorgxrdp` has dependency on `pkg-config` from host, not from build. It's very strange, given that it is placed in `nativeBuildInputs`, just like `autoconf` and `automake`, which behave correctly:
https://github.com/NixOS/nixpkgs/blob/d934204a0f8d9198e1e4515dd6fec76a139c87f0/pkgs/applications/networking/remote/xrdp/default.nix#L49
How can this be? How can I fix this?

Unfortunately, such errors seem to be fairly common in wrapped packages (which is the case with pkg-config).

I couldn't tell you why the splicing is going wrong, but perhaps overriding xrdp to use pkg-config-unwrapped will work?
If it does, something in the wrapper is causing splicing to break.

diff --git a/pkgs/applications/networking/remote/xrdp/default.nix b/pkgs/applications/networking/remote/xrdp/default.nix
index c9f679d9e124..700a040e9f14 100644
--- a/pkgs/applications/networking/remote/xrdp/default.nix
+++ b/pkgs/applications/networking/remote/xrdp/default.nix
@@ -58,6 +58,9 @@ let
       substituteInPlace configure.ac \
         --replace 'moduledir=`pkg-config xorg-server --variable=moduledir`' "moduledir=$out/lib/xorg/modules" \
         --replace 'sysconfdir="/etc"' "sysconfdir=$out/etc"
+
+      substituteInPlace bootstrap \
+        --replace-fail "command -v pkg-config" "command -v $PKG_CONFIG"
     '';

     preConfigure = "./bootstrap";
@@ -94,10 +97,13 @@ let
       substituteInPlace sesman/xauth.c --replace "xauth -q" "${xorg.xauth}/bin/xauth -q"

       substituteInPlace configure.ac --replace /usr/include/ ""
+
+      substituteInPlace bootstrap librfxcodec/bootstrap \
+        --replace-fail "command -v pkg-config" "command -v $PKG_CONFIG"
     '';

     preConfigure = ''
-      (cd librfxcodec && ./bootstrap && ./configure --prefix=$out --enable-static --disable-shared)
+      (cd librfxcodec && ./bootstrap && ./configure --prefix=$out --enable-static --disable-shared --host=${stdenv.hostPlatform.config})
       ./bootstrap
     '';
     dontDisableStatic = true;

In reply to @thefossguy:matrix.org
also, these erratas are errors in implementing the RISC-V spec in the actual Linux-capable core, individual or on SoC

Yes, the behaviour may differ from the official spec, but you still have to consider the impact.

• ERRATA_THEAD_PBMT is about page tables, it's kernel-mode specific
• ERRATA_THEAD_PMU is about performance counter overflows
• ERRATA_THEAD_CMO I don't understand enough, but you can also disable those extensions
• ERRATA_THEAD_QSPINLOCK is a case where the vendor implementation is more restricted than what the spec requires
  So the question is if these warrant not trusting the machines as build boxes. For me, these erratas are not major issues.