Description of problem:
PXE booting a client configured for UEFI and IPv6（Across the three layer protocol）, the client drops to the grub2 shell instead of displaying the expected selection menu as configured .

Version-Release number of selected component (if applicable):
Red Hat Enterprise Linux 7.4

How reproducible:
pxe booting system faills always.

Steps to Reproduce:
1. Configuring a PXE Server for UEFI-based Clients, configure a RHEL server to host TFTP and DHCPv6.
2. Copy the EFI boot image, grubx86.efi from <disc>/EFI/BOOT/* to tftp root directory.
3. Copy vmlinuz and initrd from <disc>/images/pxeboot to tftp root directory.

4.tftp root was set to /tftpboot and its contents as fallows.
bash-4.2# ls /tftpboot/ -R
/tftpboot/:
BOOTAA64.EFI  BOOTX64.EFI  EFI  efi  grubaa64.efi  grubx64.efi  initrd.img  pxelinux.0  pxelinux.cfg  vmlinuz

/tftpboot/EFI:
BOOT

/tftpboot/EFI/BOOT:
aarch64  grub.cfg  initrd.img  vmlinuz

/tftpboot/EFI/BOOT/aarch64:
initrd.img  vmlinuz

/tftpboot/efi:

/tftpboot/pxelinux.cfg:
default

5.Configure dhcpd6 

bash-4.2# cat /etc/dnsmasq.d/dnsmasq.conf
port=0
interface         =  eth_MANA
bind-interfaces
#dhcp-range=99.99.1.100, 99.99.1.200, 255.255.0.0, 12h
#dhcp-range=::fffe:6363:0164, ::fffe:6363:01c8, 112, 12h
log-queries
log-dhcp
conf-dir=/etc/dnsmasq.d
#except-interface=em1

dhcp-match=x86PC, option:client-arch, 0 #BIOS x86
dhcp-match=BC_EFI, option:client-arch, 7 #EFI x86-64
dhcp-match=AARCH64_EFI, option:client-arch, 11 #EFI AARCH64
dhcp-boot=tag:x86PC,pxelinux.0   # for Legacy BIOS detected by dhcp-match above
dhcp-boot=tag:BC_EFI,efi/BOOTX64.EFI # for UEFI arch detected by dhcp-match above
dhcp-boot=tag:AARCH64_EFI,efi/BOOTAA64.EFI # for UEFI arch detected by dhcp-match above
dhcp-option=option6:bootfile-url,tftp://[::fffe:6363:105]/BOOTX64.EFI   # for ipv6 uEFI only
tftp-root=/tftpboot

#dhcp-hostsdir=/etc/dnsmasq.d/hosts # need dnsmasq version >=2.73
dhcp-range=eth_MANA,::fffe:6362:100, ::fffe:6362:200, 112, 12h
dhcp-range=eth_MANA,::fffe:6363:132, ::fffe:6363:196, 112, 12h

6.configure tftp and enable ipv6

bash-4.2# cat /etc/xinetd.d/tftp
# default: off
# description: The tftp server serves files using the trivial file transfer \
#       protocol.  The tftp protocol is often used to boot diskless \
#       workstations, download configuration files to network-aware printers, \
#       and to start the installation process for some operating systems.
service tftp
{
    socket_type     = dgram
    protocol        = udp
    wait            = yes
    user            = root
    server          = /usr/sbin/in.tftpd
    server_args     = -s /tftpboot
    disable         = no
    per_source      = 11
    cps             = 100 2
    flags         = IPv6
    bind         =  ::fffe:6363:105
}

7.Configure client to boot in UEFI mode, and select network boot for IPv6 ( three layer protocol )

Actual results:
ient obtains IPv6 address from expected DHCP, and downloads the expected netboot image (BOOTX64.efi).  After 1-2 minutes, the client drops to the grub2 shell. The client never displays the contents of grub.

Expected results:
PXE boot client and reach the OS selection menu 

Additional info:
i found some impossible probles for reference
1) found pxe client ip but can't find three layer route
grub> net_ls_addr
efinet9 28:7b:09:c9:31:6f 0:00:00fffe:6362:1b8

grub> net_ls_routes
efinet0: loca1 O:0:0:0:0:fffe:63621b8/128 
efinet0:efinet0 0:0000:0:0:0/64 efinet0
2)Catchinf  a network packet found
13:31:10.539171 IP6 (class 0xc0, hlim 64, next-header UDP (17) payload length: 195) ::fffe:6363:105.547 > ::fffe:6363:104.547: [bad udp cksum 0xc9a1 -> 0x09cf!] dhcp6 relay-reply (linkaddr=::fffe:6362:1 peeraddr=fe80::2a7b:9ff:fec9:316f (interface-ID 0000102b...) (relay-message (dhcp6 reply (xid=6374cf (client-ID type 4) (server-ID hwaddr/time type 1 time 615370196 7ea9a37b5894) (IA_NA IAID:4252860283 T1:21600 T2:37800 (IA_ADDR ::fffe:6362:1b8 pltime:43200 vltime:43200)) (status-code Success) (opt_59))))
13:31:13.234598 IP6 (hlim 127, next-header UDP (17) payload length: 49) ::fffe:6362:1b8.1774 > ::fffe:6363:105.69: [udp sum ok]  41 RRQ "BOOTX64.EFI" octet tsize 0 blksize 1228
13:31:14.893232 IP6 (hlim 127, next-header UDP (17) payload length: 41) ::fffe:6362:1b8.1776 > ::fffe:6363:105.69: [udp sum ok]  33 RRQ "BOOTX64.EFI" octet blksize 1228
13:31:15.055866 IP6 (hlim 127, next-header UDP (17) payload length: 41) ::fffe:6362:1b8.1778 > ::fffe:6363:105.69: [udp sum ok]  33 RRQ "/grubx64.efi" octet blksize 512
13:31:15.296742 IP6 (hlim 64, next-header UDP (17) payload length: 148) ::fffe:6363:104.547 > ::fffe:6363:105.547: [udp sum ok] dhcp6 relay-fwd (linkaddr=::fffe:6362:1 peeraddr=fe80::2a7b:9ff:fec9:316f (interface-ID 0000102b...) (relay-message (dhcp6 release (xid=6474cf (client-ID type 4) (server-ID hwaddr/time type 1 time 615370196 7ea9a37b5894) (elapsed-time 0) (IA_NA IAID:4252860283 T1:4294967295 T2:4294967295 (IA_ADDR ::fffe:6362:1b8 pltime:43200 vltime:43200)))))
13:31:15.298221 IP6 (class 0xc0, hlim 64, next-header UDP (17) payload length: 120) ::fffe:6363:105.547 > ::fffe:6363:104.547: [bad udp cksum 0xc956 -> 0x32b2!] dhcp6 relay-reply (linkaddr=::fffe:6362:1 peeraddr=fe80::2a7b:9ff:fec9:316f (interface-ID 0000102b...) (relay-message (dhcp6 reply (xid=6474cf (client-ID type 4) (server-ID hwaddr/time type 1 time 615370196 7ea9a37b5894) (status-code Success))))