I'm trying to boot SLES 11 SP3 on a HP G9 DL380 server with RAID p380 in UEFI. I have this configuration in my bootloader (iPXE) :

kernel https://server/sles11-x86_64/disc1/boot/x86_64/loader/linux splash=silent install=https://xxx autoyast=https://xxx load_ramdisk=1 dud=0 textmode=0 edd=on initrd=initrd
initrd  https://server/sles11-x86_64/disc1/boot/x86_64/loader/initrd
But I'm getting a kernel panic

 VFS: Cannot open root device "(null)" or unknown-block(0,0)
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
Can you help me to solve the issue please?