image.bbclass: add function to disable SSH DNS Lookup for Qemu

This function disables the reverse DNS lookup on QEMU targets to reduce the
delay when using static IP address. By disabling DNS lookup we can save a great
deal of time during automated testing on the autobuilder (on the order of ~400
seconds per ssh tranaction). This is seen when using the testimage, there is a
delay getting logged-in from the server to target.

It's enabled for all qemu imgaes by default and can be overridden by setting
the SSH_DISABLE_DNS_LOOKUP variable.

[YOCTO #5954]

Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 29309f55cb0c39ef1444a0b683abd0d86e69cd6e..ea035fe144ceb3cb13544c1c1fc92902114c5daa 100644 (file)
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -304,6 +304,16 @@ ssh_allow_empty_password () {
        fi
 }
 
+# Disable DNS lookups, the SSH_DISABLE_DNS_LOOKUP can be overridden to allow
+# distros to choose not to take this change
+SSH_DISABLE_DNS_LOOKUP ?= " ssh_disable_dns_lookup ; "
+ROOTFS_POSTPROCESS_COMMAND_append_qemuall = "${SSH_DISABLE_DNS_LOOKUP}"
+ssh_disable_dns_lookup () {
+       if [ -e ${IMAGE_ROOTFS}${sysconfdir}/ssh/sshd_config ]; then
+               sed -i -e 's:#UseDNS yes:UseDNS no:' ${IMAGE_ROOTFS}${sysconfdir}/ssh/sshd_config
+       fi
+}
+
 # Enable postinst logging if debug-tweaks is enabled
 postinst_enable_logging () {
        mkdir -p ${IMAGE_ROOTFS}${sysconfdir}/default