pxe boot for diskless server, no filesystem could mount root

[fore...@gmail.com]

Hi:

   Now We are ready use coreos on several diskless servers. We enter the coreos sdk. We can not boot the servers using the official vmlinuz and cpio image. So, First, we compile the coreos kernel and get an bzImage. Then, we use the the sdk to get and cpio image. We use the bzImage kernel and cpio image to boot the servers. The server can boot when using the bzImage. But when the system is ready to chroot, we get the following error:

   [    6.648945] registered taskstats version 1

[    6.653050] Loading compiled-in X.509 certificates

[    6.658793] Loaded X.509 cert 'Build time autogenerated kernel key: b6421bc3fbb5bdd55f6d4cd3265754432f6d81ae'

[    6.670128] rtc_cmos 00:03: setting system clock to 2016-06-02 04:39:49 UTC (1464842389)

[    6.678527] List of all partitions:

[    6.682024] No filesystem could mount root, tried: 

[    6.686922] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)

[    6.695174] CPU: 2 PID: 1 Comm: swapper/0 Tainted: G          I     4.5.4-coreos #3

[    6.702816] Hardware name:  /, BIOS CPM_2.4.06 05/29/2013

[    6.708556]  0000000000000086 000000007085c1d6 ffff88085c67bdd8 ffffffffbc2e6ab3

[    6.716009]  ffffffffbc7b6120 ffff88085c67be70 ffff88085c67be60 ffffffffbc15d747

[    6.723463]  ffffffff00000010 ffff88085c67be70 ffff88085c67be08 000000007085c1d6

[    6.730918] Call Trace:

 How can we resolve the error to boot the servers normally. Thanks!

[kyle....@coreos.com]

This an error mounting the root partition because the kernel does not know how to access the file system to start systemd. Could you share the section of your pxelinux.cfg that looks like the section below:

label coreos

  menu default

  kernel coreos_production_pxe.vmlinuz

  append initrd=coreos_production_pxe_image.cpio.gz cloud-config-url=http://example.com/pxe-cloud-config.yml

Thanks,

Kyle Brown