linux-initrd: Add virtio modules to '%base-initrd-modules'.

Fixes a regression in installation tests, whereby 'guix system init'
would report that virtio modules are missing for the target devices.
In practice virtio modules were always available since 'base-initrd' was
always called with #:virtio? #t.  This commit simply moves them to
'%base-initrd-modules' so that 'guix system' knows they're available.

Reported by Danny Milosavljevic <dannym@scratchpost.org> at
<https://debbugs.gnu.org/cgi/bugreport.cgi?bug=30629#112>.

* gnu/system/linux-initrd.scm (default-initrd-modules): Add virtio
modules.
(base-initrd): Remove #:virtio? and 'virtio-modules'.
* gnu/system/vm.scm (expression->derivation-in-linux-vm)
(system-qemu-image, virtualized-operating-system): Remove uses of
 #:virtio?.
* doc/guix.texi (Initial RAM Disk): Update 'base-initrd' doc.

doc/guix.texi

@@ -19893,18 +19893,18 @@ to it are lost.
 
 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
        [#:mapped-devices '()] [#:qemu-networking? #f] [#:volatile-root? #f]@
-       [#:virtio? #t] [#:extra-modules '()]
+       [#:linux-modules '()]
-Return a monadic derivation that builds a generic initrd.  @var{file-systems} is
+Return a monadic derivation that builds a generic initrd, with kernel
-a list of file systems to be mounted by the initrd like for @code{raw-initrd}.
+modules taken from @var{linux}.  @var{file-systems} is a list of file-systems to be
-@var{mapped-devices}, @var{qemu-networking?} and @var{volatile-root?}
+mounted by the initrd, possibly in addition to the root file system specified
-also behaves as in @code{raw-initrd}.
+on the kernel command line via @code{--root}.  @var{mapped-devices} is a list of device
+mappings to realize before @var{file-systems} are mounted.
 
-When @var{virtio?} is true, load additional modules so that the
+@var{qemu-networking?} and @var{volatile-root?} behaves as in @code{raw-initrd}.
-initrd can be used as a QEMU guest with para-virtualized I/O drivers.
 
 The initrd is automatically populated with all the kernel modules necessary
-for @var{file-systems} and for the given options.  However, additional kernel
+for @var{file-systems} and for the given options.  Additional kernel
-modules can be listed in @var{extra-modules}.  They will be added to the initrd, and
+modules can be listed in @var{linux-modules}.  They will be added to the initrd, and
 loaded at boot time in the order in which they appear.
 @end deffn
 

gnu/system/linux-initrd.scm

@@ -280,6 +280,11 @@ FILE-SYSTEMS."
 
 (define* (default-initrd-modules #:optional (system (%current-system)))
   "Return the list of modules included in the initrd by default."
+  (define virtio-modules
+    ;; Modules for Linux para-virtualized devices, for use in QEMU guests.
+    '("virtio_pci" "virtio_balloon" "virtio_blk" "virtio_net"
+      "virtio_console"))
+
   `("ahci"                                  ;for SATA controllers
     "usb-storage" "uas"                     ;for the installation image etc.
     "usbhid" "hid-generic" "hid-apple"      ;keyboards during early boot
@@ -288,7 +293,9 @@ FILE-SYSTEMS."
     ,@(if (string-match "^(x86_64|i[3-6]86)-" system)
           '("pata_acpi" "pata_atiixp"    ;for ATA controllers
             "isci")                      ;for SAS controllers like Intel C602
-          '())))
+          '())
+
+    ,@virtio-modules))
 
 (define-syntax %base-initrd-modules
   ;; This more closely matches our naming convention.
@@ -301,7 +308,6 @@ FILE-SYSTEMS."
                       (mapped-devices '())
                       qemu-networking?
                       volatile-root?
-                      (virtio? #t)
                       (extra-modules '())         ;deprecated
                       (on-error 'debug))
   "Return a monadic derivation that builds a generic initrd, with kernel
@@ -312,25 +318,13 @@ mappings to realize before FILE-SYSTEMS are mounted.
 
 QEMU-NETWORKING? and VOLATILE-ROOT? behaves as in raw-initrd.
 
-When VIRTIO? is true, load additional modules so the initrd can
-be used as a QEMU guest with the root file system on a para-virtualized block
-device.
-
 The initrd is automatically populated with all the kernel modules necessary
-for FILE-SYSTEMS and for the given options.  However, additional kernel
+for FILE-SYSTEMS and for the given options.  Additional kernel
-modules can be listed in EXTRA-MODULES.  They will be added to the initrd, and
+modules can be listed in LINUX-MODULES.  They will be added to the initrd, and
 loaded at boot time in the order in which they appear."
-  (define virtio-modules
-    ;; Modules for Linux para-virtualized devices, for use in QEMU guests.
-    '("virtio_pci" "virtio_balloon" "virtio_blk" "virtio_net"
-      "virtio_console"))
-
   (define linux-modules*
     ;; Modules added to the initrd and loaded from the initrd.
     `(,@linux-modules
-      ,@(if (or virtio? qemu-networking?)
-            virtio-modules
-            '())
       ,@(file-system-modules file-systems)
       ,@(if volatile-root?
             '("overlay")

gnu/system/vm.scm

@@ -144,7 +144,6 @@ made available under the /xchg CIFS share."
                          (base-initrd %linux-vm-file-systems
                                       #:linux linux
                                       #:linux-modules %base-initrd-modules
-                                      #:virtio? #t
                                       #:qemu-networking? #t))))
 
     (define builder
@@ -513,12 +512,7 @@ of the GNU system as described by OS."
 
 
   (let ((os (operating-system (inherit os)
-              ;; Use an initrd with the whole QEMU shebang.
+              ;; Assume we have an initrd with the whole QEMU shebang.
-              (initrd (lambda (file-systems . rest)
-                        (apply (operating-system-initrd os)
-                               file-systems
-                               #:virtio? #t
-                               rest)))
 
               ;; Force our own root file system.  Refer to it by UUID so that
               ;; it works regardless of how the image is used ("qemu -hda",
@@ -615,7 +609,6 @@ environment with the store shared with the host.  MAPPINGS is a list of
               (apply (operating-system-initrd os)
                      file-systems
                      #:volatile-root? #t
-                     #:virtio? #t
                      rest)))
 
     ;; Disable swap.