61/64: build: vm: Fix arm32 support.

[guix-commits]

mothacehe pushed a commit to branch wip-cross-system
in repository guix.

commit d99041dfde21962619aab388b708d20df53fe914
Author: Mathieu Othacehe <address@hidden>
Date:   Fri Aug 23 09:51:33 2019 +0200

    build: vm: Fix arm32 support.
    
    * gnu/build/vm.scm (load-in-linux-vm): Disable qemu highmem support on ARM32
    systems.
---
 gnu/build/vm.scm | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/gnu/build/vm.scm b/gnu/build/vm.scm
index a5d9fef..b85398e 100644
--- a/gnu/build/vm.scm
+++ b/gnu/build/vm.scm
@@ -102,6 +102,14 @@ the #:references-graphs parameter of 'derivation'."
       ;; hardware limits imposed by other machines.
       ,@(if target-arm32? '("-M" "virt") '())
 
+      ;; On ARM32, if the kernel is built without LPAE support, ECAM conflicts
+      ;; with VIRT_PCIE_MMIO causing PCI devices not to show up.  Disable
+      ;; explicitely highmem to fix it.
+      ;; See: https://bugs.launchpad.net/qemu/+bug/1790975.
+      ,@(if target-arm32?
+            '("-machine" "highmem=off")
+            '())
+
       ;; Only enable kvm if we see /dev/kvm exists.  This allows users without
       ;; hardware virtualization to still use these commands.  KVM support is
       ;; still buggy on some ARM32 boards. Do not use it even if available.