u-boot/doc/README.iscsi

1 # iSCSI booting with U-Boot and iPXE
5 U-Boot has only a reduced set of supported network protocols. The focus for
13 These protocols are insecure. The client cannot validate the authenticity
14 of the contacted servers. And the server cannot verify the identity of the
34 An alternative to implementing these protocols in U-Boot is to use an existing
35 software that can run on top of U-Boot. iPXE[1] is the "swiss army knife" of
40 run by U-Boot.
44 U-Boot loads the EFI application iPXE snp.efi using the bootefi command. This
46 U-Boot.
56 uses the ConnectController boot service of U-Boot to request U-Boot to connect a
57 file system driver. U-Boot reads from the iSCSI drive via the block IO protocol
59 protocol. Now iPXE can call the simple file protocol to load GRUB[2]. U-Boot
65                   +--------+         +--------+
67                   | U-Boot |========>| iPXE   |
69     +--------+    |        | DHCP    |        |
74     +--------+    |        | Response|        |
77     +--------+    |        | HTTPS   |        |
82     +--------+    |        |         |        |
85     +--------+    |        | iSCSI   |        |
91     |        |<===|********|<========|        |       +--------+
97     |        |<===|********|<========|********|<======|        |      +--------+
101     +--------+    +--------+         +--------+       +--------+      |        |
109 but neither U-Boot nor iPXE does support this. So we should at least separate
117 For running iPXE on arm64 the bin-arm64-efi/snp.efi build target is needed::
121     make bin-arm64-efi/snp.efi -j6 EMBED=myscript.ipxe
131 iPXE by default will put the CPU to rest when waiting for input. U-Boot does
132 not wake it up due to missing interrupt support. To avoid this behavior create
154 ### Open-iSCSI
157 the replacement timer to a high value [3]:
165 * [1](https://ipxe.org) https://ipxe.org - iPXE open source boot firmware
166 * [2](https://www.gnu.org/software/grub/) https://www.gnu.org/software/grub/ -
168 * [3](https://github.com/open-iscsi/open-iscsi/blob/master/README)
169      https://github.com/open-iscsi/open-iscsi/blob/master/README -
170      Open-iSCSI README