common: Make U-Boot's auxiliary environment accessable from Infix

This is not the full environment used by U-Boot, just the bits needed
for U-Boot to know which slot to boot and for Infix to know how the
boot process went.

U-Boot will selectively import/export only these keys during boot,
which avoids a malicious user from altering the boot in a way that
might bypass signature validation.

board/common/rootfs/etc/fstab

@@ -18,6 +18,7 @@ hostfs		/host		9p		nofail,cache=none,msize=16384	0	0
 # /home, /root, and /var, are determined dynamically by /lib/infix/mnt
 # depending on the available devices.
 mnttmp		/mnt/tmp	tmpfs		defaults			0	0
+LABEL=aux	/mnt/aux	auto		noatime,nodiratime,noauto	0	0
 LABEL=var	/mnt/var	auto		noatime,nodiratime,noauto	0	0
 LABEL=cfg	/mnt/cfg	auto		noatime,nodiratime,noauto	0	0
 /lib/infix/mnt# /cfg		helper		none				0	0

board/common/rootfs/etc/fw_env.config

@@ -0,0 +1 @@
+/mnt/aux/uboot.env 0 0x4000

board/common/rootfs/lib/infix/mnt

@@ -77,6 +77,11 @@ if ! logger -? |grep -q "Log to kernel"; then
     opt="-c"
 fi
 
+if ! mount_rw aux >/dev/null 2>&1; then
+    logger $opt -p user.warn -t "$nm" \
+	   "No auxiliary partition found, software updates not supported."
+fi
+
 varsrc=/mnt/var
 if ! mount_rw var >/dev/null 2>&1; then
     logger $opt -p user.warn -t "$nm" \

board/common/uboot/aux-env.txt

@@ -0,0 +1,4 @@
+BOOT_ORDER=primary secondary net
+BOOT_primary_LEFT=1
+BOOT_secondary_LEFT=1
+BOOT_net_LEFT=1

configs/aarch64_defconfig

@@ -115,6 +115,9 @@ BR2_PACKAGE_HOST_GENIMAGE=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS_FIT_SUPPORT=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS_FIT_SIGNATURE_SUPPORT=y
+BR2_PACKAGE_HOST_UBOOT_TOOLS_ENVIMAGE=y
+BR2_PACKAGE_HOST_UBOOT_TOOLS_ENVIMAGE_SOURCE="$(BR2_EXTERNAL_INFIX_PATH)/board/common/uboot/aux-env.txt"
+BR2_PACKAGE_HOST_UBOOT_TOOLS_ENVIMAGE_SIZE="0x4000"
 BR2_PACKAGE_CLIXON_RESTCONF_FCGI=y
 BR2_PACKAGE_FACTORY=y
 BR2_PACKAGE_FINIT_SULOGIN=y