2 files changed, 20 insertions, 5 deletions
diff --git a/gnu/system/mapped-devices.scm b/gnu/system/mapped-devices.scm
index af73dc608c..a874666463 100644
--- a/gnu/system/mapped-devices.scm
+++ b/gnu/system/mapped-devices.scm
@@ -157,7 +157,10 @@ these lines:
    ;; @dots{}
    (initrd-modules (append (list~{ ~s~})
                            %base-initrd-modules)))
-@end example\n")
+@end example
+
+If you think this diagnostic is inaccurate, use the @option{--skip-checks}
+option of @command{guix system}.\n")
                                missing)))
                 (&error-location
                  (location (source-properties->location location)))))))))
diff --git a/gnu/system/vm.scm b/gnu/system/vm.scm
index 91e117b9f3..a1b595d45d 100644
--- a/gnu/system/vm.scm
+++ b/gnu/system/vm.scm
@@ -99,21 +99,28 @@
           (device "store")
           (type "9p")
           (needed-for-boot? #t)
-          (options "trans=virtio")
+          (flags '(read-only))
+          (options "trans=virtio,cache=loose")
           (check? #f))
+
+        ;; The 9p documentation says that cache=loose is "intended for
+        ;; exclusive, read-only mounts", without additional details.  In
+        ;; practice it seems to work well for these, and it's much faster than
+        ;; the default cache=none, especially when copying and registering
+        ;; store items.
         (file-system
           (mount-point "/xchg")
           (device "xchg")
           (type "9p")
           (needed-for-boot? #t)
-          (options "trans=virtio")
+          (options "trans=virtio,cache=loose")
           (check? #f))
         (file-system
           (mount-point "/tmp")
           (device "tmp")
           (type "9p")
           (needed-for-boot? #t)
-          (options "trans=virtio")
+          (options "trans=virtio,cache=loose")
           (check? #f))))
 
 (define not-config?
@@ -390,7 +397,12 @@ the image."
                                  #:closures graphs
                                  #:copy-closures? #$copy-inputs?
                                  #:register-closures? #$register-closures?
-                                 #:system-directory #$os-drv))
+                                 #:system-directory #$os-drv
+
+                                 ;; Disable deduplication to speed things up,
+                                 ;; and because it doesn't help much for a
+                                 ;; single system generation.
+                                 #:deduplicate? #f))
                     (root-size  #$(if (eq? 'guess disk-image-size)
                                       #~(max
                                          ;; Minimum 20 MiB root size