Add NO_BOOT variable

diff --git a/README.md b/README.md
index 0eff63b9fca965ba8738b7895eb60331c1dc325f..24421af689d8bc40260ae6a72b48d825bac48a9e 100644 (file)
--- a/README.md
+++ b/README.md
@@ -606,6 +606,13 @@ The following variables are interpreted in the novaboot script:
     parameters. If this variable is defined and non-empty, the variable
     HYPERVISOR\_PARAMS is not used.
 
+- NO\_BOOT
+
+    If this variable is 1, the system is not booted. This is currently
+    only implemented for U-Boot bootloader where it is useful for
+    interacting with the bootloader without booting the system - e.g. for
+    flashing.
+
 - QEMU
 
     Use a specific qemu binary (can be overridden with **-Q**) and flags

diff --git a/novaboot b/novaboot
index 9b2c3df2930414e52194c3069c077d6a4a868958..d0d097d9fb05294d5a157de2ed9a698ffd5e02e4 100755 (executable)
--- a/novaboot
+++ b/novaboot
@@ -1016,7 +1016,7 @@ if (defined $uboot) {
     }
 
     # Boot the system if there are some load lines in the script
-    if (scalar(@$modules) > 0) {
+    if (scalar(@$modules) > 0 && !$variables->{NO_BOOT}) {
        my ($kbin, $kcmd) = split(' ', shift(@$modules), 2);
        my $dtb;
        @$modules = map { if (/\.dtb$/) { $dtb=$_; (); } else { $_ } } @$modules;
@@ -1761,6 +1761,13 @@ contain the name of the kernel image as well as its command line
 parameters. If this variable is defined and non-empty, the variable
 HYPERVISOR_PARAMS is not used.
 
+=item NO_BOOT
+
+If this variable is 1, the system is not booted. This is currently
+only implemented for U-Boot bootloader where it is useful for
+interacting with the bootloader without booting the system - e.g. for
+flashing.
+
 =item QEMU
 
 Use a specific qemu binary (can be overridden with B<-Q>) and flags