Yes, I hit the same roadblock on my Pi0. vc4 can be enabled on armv6h and works fine.
Had to patch it like this and disable libunwind since it doesn't compile otherwise.
$this->bbcode_second_pass_code('', '
diff -urN a/PKGBUILD b/PKGBUILD
--- a/PKGBUILD 2018-04-02 19:59:08.117956780 +0200
+++ b/PKGBUILD 2018-04-02 19:59:00.127956511 +0200
@@ -9,7 +9,7 @@
pkgname=('mesa' 'libva-mesa-driver')
pkgver=17.3.7
pkgrel=1
-arch=('x86_64')
+arch=('x86_64' 'armv6h')
makedepends=('python2-mako' 'libxml2' 'libx11' 'glproto' 'libdrm' 'dri2proto' 'dri3proto' 'presentproto'
'libxshmfence' 'libxxf86vm' 'libxdamage' 'libvdpau' 'libva' 'wayland' 'wayland-protocols'
'elfutils' 'llvm' 'libomxil-bellagio' 'clang' 'libglvnd' 'lm_sensors')
@@ -40,7 +40,7 @@
cd ${srcdir}/mesa-${pkgver}
[[ $CARCH == "armv7h" ]] && GALLIUM=",etnaviv,imx"
- [[ $CARCH == "armv7h" || $CARCH == "aarch64" ]] && GALLIUM+=",vc4"
+ [[ $CARCH == "arm" || $CARCH == "armv6h" || $CARCH == "armv7h" || $CARCH == "aarch64" ]] && GALLIUM+=",vc4"
[[ $CARCH == arm || $CARCH == armv6h ]] && LIBS="-latomic"
LIBS=$LIBS ./configure --prefix=/usr \
@@ -49,6 +49,7 @@
--with-dri-drivers=nouveau,swrast \
--with-platforms=x11,drm,wayland \
--disable-xvmc \
+ --disable-libunwind \
--enable-llvm \
--enable-llvm-shared-libs \
--enable-shared-glapi \
')
Here is a compiled mesa package with vc4 enabled for armv6h :
https://v.teknik.io/v/Lfaj7or
$this->bbcode_second_pass_code('', '
wget https://u.teknik.io/0WMlz.xz -O mesa-17.3.7-1-armv6h.pkg.tar.xz
')