[bug#30572] [PATCH 4/7] gnu: When building in a VM, share a temporary directory.

[Chris Marusich <cmmarusich@gmail.com>]

* gnu/build/vm.scm (load-in-linux-vm): Make a shared temporary directory
  available in the VM.
* gnu/system/vm.scm (%linux-vm-file-systems): Add a corresponding entry.
---
 gnu/build/vm.scm  |  7 +++++++
 gnu/system/vm.scm | 12 ++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/gnu/build/vm.scm b/gnu/build/vm.scm
index 6380df0a1..806744a64 100644
--- a/gnu/build/vm.scm
+++ b/gnu/build/vm.scm
@@ -128,6 +128,7 @@ the #:references-graphs parameter of 'derivation'."
       (error "qemu-img failed")))
 
   (mkdir "xchg")
+  (mkdir "tmp")
 
   (match references-graphs
     ((graph-files ...)
@@ -149,6 +150,12 @@ the #:references-graphs parameter of 'derivation'."
                   "-virtfs"
                   (string-append "local,id=xchg_dev,path=xchg"
                                  ",security_model=none,mount_tag=xchg")
+                  "-virtfs"
+                  ;; Some programs require more space in /tmp than is normally
+                  ;; available in the guest.  Accommodate such programs by
+                  ;; sharing a temporary directory.
+                  (string-append "local,id=tmp_dev,path=tmp"
+                                 ",security_model=none,mount_tag=tmp")
                   "-kernel" linux
                   "-initrd" initrd
                   "-append" (string-append "console=ttyS0 --load="
diff --git a/gnu/system/vm.scm b/gnu/system/vm.scm
index ae8780d2e..d239fa56a 100644
--- a/gnu/system/vm.scm
+++ b/gnu/system/vm.scm
@@ -4,6 +4,7 @@
 ;;; Copyright © 2016, 2017 Leo Famulari <leo@famulari.name>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2017 Marius Bakke <mbakke@fastmail.com>
+;;; Copyright © 2018 Chris Marusich <cmmarusich@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -87,8 +88,8 @@
 ;;; Code:
 
 (define %linux-vm-file-systems
-  ;; File systems mounted for 'derivation-in-linux-vm'.  The store and /xchg
-  ;; directory are shared with the host over 9p.
+  ;; File systems mounted for 'derivation-in-linux-vm'.  These are shared with
+  ;; the host over 9p.
   (list (file-system
           (mount-point (%store-prefix))
           (device "store")
@@ -102,6 +103,13 @@
           (type "9p")
           (needed-for-boot? #t)
           (options "trans=virtio")
+          (check? #f))
+        (file-system
+          (mount-point "/tmp")
+          (device "tmp")
+          (type "9p")
+          (needed-for-boot? #t)
+          (options "trans=virtio")
           (check? #f))))
 
 (define* (expression->derivation-in-linux-vm name exp
-- 
2.15.1