board/qemu: ensure root is available before mounting it

On my machine, it happens once in a while that the virtualised machine
boots too fast for the rootfs to be available at the time the kernel
tries to mount it.

For example, board/qemu/arm-vexpress/readme.txt suggested changing
"-smp 1" up to "-smp 4". But doing so here causes a kernel panic:

    VFS: Cannot open root device "mmcblk0" or unknown-block(0,0): error -6
    Please append a correct "root=" boot option; here are the available partitions:
    1f00          131072 mtdblock0
     (driver?)
    1f01           32768 mtdblock1
     (driver?)
    Kernel panic - not syncing: VFS: Unable to mount root fs on
    unknown-block(0,0)

So, add the oh-so-useful 'rootwait' option to all kernel command lines
for qemu defconfigs.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Mark Corbin <mark.corbin@embecosm.com>
Cc: Matt Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 626c9705d29ec93610e87517aee771c2ea500f5d)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

board/qemu/aarch64-virt/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-aarch64 -M virt -cpu cortex-a53 -nographic -smp 1 -kernel output/images/Image -append "root=/dev/vda console=ttyAMA0" -netdev user,id=eth0 -device virtio-net-device,netdev=eth0 -drive file=output/images/rootfs.ext4,if=none,format=raw,id=hd0 -device virtio-blk-device,drive=hd0
+  qemu-system-aarch64 -M virt -cpu cortex-a53 -nographic -smp 1 -kernel output/images/Image -append "rootwait root=/dev/vda console=ttyAMA0" -netdev user,id=eth0 -device virtio-net-device,netdev=eth0 -drive file=output/images/rootfs.ext4,if=none,format=raw,id=hd0 -device virtio-blk-device,drive=hd0
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/arm-versatile/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-arm -M versatilepb -kernel output/images/zImage -dtb output/images/versatile-pb.dtb -drive file=output/images/rootfs.ext2,if=scsi,format=raw -append "root=/dev/sda console=ttyAMA0,115200" -serial stdio -net nic,model=rtl8139 -net user
+  qemu-system-arm -M versatilepb -kernel output/images/zImage -dtb output/images/versatile-pb.dtb -drive file=output/images/rootfs.ext2,if=scsi,format=raw -append "rootwait root=/dev/sda console=ttyAMA0,115200" -serial stdio -net nic,model=rtl8139 -net user
 
 Or for the noMMU emulation:
 

board/qemu/arm-vexpress/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-arm -M vexpress-a9 -smp 1 -m 256 -kernel output/images/zImage -dtb output/images/vexpress-v2p-ca9.dtb -drive file=output/images/rootfs.ext2,if=sd,format=raw -append "console=ttyAMA0,115200 root=/dev/mmcblk0" -serial stdio -net nic,model=lan9118 -net user
+  qemu-system-arm -M vexpress-a9 -smp 1 -m 256 -kernel output/images/zImage -dtb output/images/vexpress-v2p-ca9.dtb -drive file=output/images/rootfs.ext2,if=sd,format=raw -append "console=ttyAMA0,115200 rootwait root=/dev/mmcblk0" -serial stdio -net nic,model=lan9118 -net user
 
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer.

board/qemu/m68k-q800/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-m68k -M q800 -kernel output/images/vmlinux -nographic -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/sda console=ttyS0"
+ qemu-system-m68k -M q800 -kernel output/images/vmlinux -nographic -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/sda console=ttyS0"
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/mips32r2-malta/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-mips -M malta -kernel output/images/vmlinux -serial stdio -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/hda" -net nic,model=pcnet -net user
+ qemu-system-mips -M malta -kernel output/images/vmlinux -serial stdio -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda" -net nic,model=pcnet -net user
 
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer. No keyboard support has been

board/qemu/mips32r2el-malta/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-mipsel -M malta -kernel output/images/vmlinux -serial stdio -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/hda" -net nic,model=pcnet -net user
+ qemu-system-mipsel -M malta -kernel output/images/vmlinux -serial stdio -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda" -net nic,model=pcnet -net user
 
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer. No keyboard support has been

board/qemu/mips32r6-malta/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-qemu-system-mips -M malta -cpu mips32r6-generic -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/hda" -nographic
+qemu-system-mips -M malta -cpu mips32r6-generic -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda" -nographic
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/mips32r6el-malta/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-qemu-system-mipsel -M malta -cpu mips32r6-generic -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/hda" -net nic,model=pcnet -net user -nographic
+qemu-system-mipsel -M malta -cpu mips32r6-generic -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda" -net nic,model=pcnet -net user -nographic
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/mips64-malta/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-mips64 -M malta -kernel output/images/vmlinux -serial stdio -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/hda"
+ qemu-system-mips64 -M malta -kernel output/images/vmlinux -serial stdio -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda"
 
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer.

board/qemu/mips64el-malta/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-mips64el -M malta -kernel output/images/vmlinux -serial stdio -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/hda"
+ qemu-system-mips64el -M malta -kernel output/images/vmlinux -serial stdio -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda"
 
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer.

board/qemu/mips64r6-malta/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-mips64 -M malta -cpu I6400 -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/hda" -nographic
+ qemu-system-mips64 -M malta -cpu I6400 -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda" -nographic
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/mips64r6el-malta/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-mips64el -M malta -cpu I6400 -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/hda" -nographic
+ qemu-system-mips64el -M malta -cpu I6400 -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda" -nographic
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/ppc-g3beige/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-ppc -M g3beige -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "console=ttyS0 root=/dev/hda" -serial stdio -net nic,model=rtl8139 -net user
+  qemu-system-ppc -M g3beige -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "console=ttyS0 rootwait root=/dev/hda" -serial stdio -net nic,model=rtl8139 -net user
 
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer.

board/qemu/ppc64-e5500/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-ppc64 -M ppce500 -cpu e5500 -m 256 -kernel output/images/uImage -drive file=output/images/rootfs.ext2,if=virtio,format=raw -append "console=ttyS0 root=/dev/vda" -serial mon:stdio -nographic
+ qemu-system-ppc64 -M ppce500 -cpu e5500 -m 256 -kernel output/images/uImage -drive file=output/images/rootfs.ext2,if=virtio,format=raw -append "console=ttyS0 rootwait root=/dev/vda" -serial mon:stdio -nographic
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/ppc64-pseries/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
- qemu-system-ppc64 -M pseries -cpu POWER7 -m 256 -kernel output/images/vmlinux -append "console=hvc0 root=/dev/sda" -drive file=output/images/rootfs.ext2,if=scsi,index=0,format=raw -serial stdio -display curses
+ qemu-system-ppc64 -M pseries -cpu POWER7 -m 256 -kernel output/images/vmlinux -append "console=hvc0 rootwait root=/dev/sda" -drive file=output/images/rootfs.ext2,if=scsi,index=0,format=raw -serial stdio -display curses
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/ppc64le-pseries/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-qemu-system-ppc64 -M pseries -cpu POWER8 -m 256 -kernel output/images/vmlinux -append "console=hvc0 root=/dev/sda" -drive file=output/images/rootfs.ext2,if=scsi,index=0,format=raw -serial stdio -display curses
+qemu-system-ppc64 -M pseries -cpu POWER8 -m 256 -kernel output/images/vmlinux -append "console=hvc0 rootwait root=/dev/sda" -drive file=output/images/rootfs.ext2,if=scsi,index=0,format=raw -serial stdio -display curses
 
 The login prompt will appear in the terminal window.
 

board/qemu/riscv32-virt/readme.txt

@@ -1,6 +1,6 @@
 Run Linux in emulation with:
 
-  qemu-system-riscv32 -M virt -kernel output/images/fw_jump.elf -device loader,file=output/images/Image,addr=0x80400000 -append "root=/dev/vda ro" -drive file=output/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -netdev user,id=net0 -device virtio-net-device,netdev=net0 -nographic
+  qemu-system-riscv32 -M virt -kernel output/images/fw_jump.elf -device loader,file=output/images/Image,addr=0x80400000 -append "rootwait root=/dev/vda ro" -drive file=output/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -netdev user,id=net0 -device virtio-net-device,netdev=net0 -nographic
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/riscv64-virt/readme.txt

@@ -1,6 +1,6 @@
 Run Linux in emulation with:
 
-  qemu-system-riscv64 -M virt -kernel output/images/fw_jump.elf -device loader,file=output/images/Image,addr=0x80200000 -append "root=/dev/vda ro" -drive file=output/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -netdev user,id=net0 -device virtio-net-device,netdev=net0 -nographic
+  qemu-system-riscv64 -M virt -kernel output/images/fw_jump.elf -device loader,file=output/images/Image,addr=0x80200000 -append "rootwait root=/dev/vda ro" -drive file=output/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -netdev user,id=net0 -device virtio-net-device,netdev=net0 -nographic
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/sh4-r2d/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-sh4 -M r2d -kernel output/images/zImage -drive file=output/images/rootfs.ext2,if=ide,format=raw -append "root=/dev/sda console=ttySC1,115200 noiotrap" -serial null -serial stdio -net nic,model=rtl8139 -net user
+  qemu-system-sh4 -M r2d -kernel output/images/zImage -drive file=output/images/rootfs.ext2,if=ide,format=raw -append "rootwait root=/dev/sda console=ttySC1,115200 noiotrap" -serial null -serial stdio -net nic,model=rtl8139 -net user
 
 The login prompt will appear in the terminal that started Qemu.
 The graphical window is the framebuffer.

board/qemu/sh4eb-r2d/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-sh4eb -M r2d -kernel output/images/zImage -drive file=output/images/rootfs.ext2,if=ide,format=raw -append "root=/dev/sda console=ttySC1,115200 noiotrap" -serial null -serial stdio -net nic,model=rtl8139 -net user
+  qemu-system-sh4eb -M r2d -kernel output/images/zImage -drive file=output/images/rootfs.ext2,if=ide,format=raw -append "rootwait root=/dev/sda console=ttySC1,115200 noiotrap" -serial null -serial stdio -net nic,model=rtl8139 -net user
 
 The login prompt will appear in the terminal that started Qemu.
 The graphical window is the framebuffer.

board/qemu/sparc-ss10/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-sparc -M SS-10 -kernel output/images/zImage -drive file=output/images/rootfs.ext2,format=raw -append "root=/dev/sda console=ttyS0,115200" -serial stdio -net nic,model=lance -net user
+  qemu-system-sparc -M SS-10 -kernel output/images/zImage -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/sda console=ttyS0,115200" -serial stdio -net nic,model=lance -net user
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/sparc64-sun4u/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-sparc64 -M sun4u -kernel output/images/vmlinux -append "root=/dev/sda console=ttyS0,115200" -serial stdio -drive file=output/images/rootfs.ext2,format=raw -net nic,model=e1000 -net user
+  qemu-system-sparc64 -M sun4u -kernel output/images/vmlinux -append "rootwait root=/dev/sda console=ttyS0,115200" -serial stdio -drive file=output/images/rootfs.ext2,format=raw -net nic,model=e1000 -net user
 
 The login prompt will appear in the terminal that started Qemu.
 

board/qemu/x86/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-i386 -M pc -kernel output/images/bzImage -drive file=output/images/rootfs.ext2,if=virtio,format=raw -append "root=/dev/vda" -net nic,model=virtio -net user
+  qemu-system-i386 -M pc -kernel output/images/bzImage -drive file=output/images/rootfs.ext2,if=virtio,format=raw -append "rootwait root=/dev/vda" -net nic,model=virtio -net user
 
 Optionally add -smp N to emulate a SMP system with N CPUs.
 

board/qemu/x86_64/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-x86_64 -M pc -kernel output/images/bzImage -drive file=output/images/rootfs.ext2,if=virtio,format=raw -append "root=/dev/vda" -net nic,model=virtio -net user
+  qemu-system-x86_64 -M pc -kernel output/images/bzImage -drive file=output/images/rootfs.ext2,if=virtio,format=raw -append "rootwait root=/dev/vda" -net nic,model=virtio -net user
 
 Optionally add -smp N to emulate a SMP system with N CPUs.