[U-Boot] [PATCH 1/1] doc: README.iscsi: make compatible with restructured text
Heinrich Schuchardt
xypron.glpk at gmx.de
Sun Jul 29 11:50:50 UTC 2018
The Sphinx documentation system uses restructured text.
Make the README.iscsi file compatible.
Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
doc/README.iscsi | 130 +++++++++++++++++++++++++----------------------
1 file changed, 68 insertions(+), 62 deletions(-)
diff --git a/doc/README.iscsi b/doc/README.iscsi
index cb71c6e7446..d8880415e32 100644
--- a/doc/README.iscsi
+++ b/doc/README.iscsi
@@ -1,6 +1,8 @@
-# iSCSI booting with U-Boot and iPXE
+iSCSI booting with U-Boot and iPXE
+==================================
-## Motivation
+Motivation
+----------
U-Boot has only a reduced set of supported network protocols. The focus for
network booting has been on UDP based protocols. A TCP stack and HTTP support
@@ -32,14 +34,15 @@ via HTTPS and to download any other files needed for booting via iSCSI from the
same target where the operating system is installed.
An alternative to implementing these protocols in U-Boot is to use an existing
-software that can run on top of U-Boot. iPXE is the "swiss army knife" of
+software that can run on top of U-Boot. iPXE[1] is the "swiss army knife" of
network booting. It supports both HTTPS and iSCSI. It has a scripting engine for
fine grained control of the boot process and can provide a command shell.
iPXE can be built as an EFI application (named snp.efi) which can be loaded and
run by U-Boot.
-## Boot sequence
+Boot sequence
+-------------
U-Boot loads the EFI application iPXE snp.efi using the bootefi command. This
application has network access via the simple network protocol offered by
@@ -56,67 +59,68 @@ For a selected iSCSI target iPXE sets up a handle with the block IO protocol. It
uses the ConnectController boot service of U-Boot to request U-Boot to connect a
file system driver. U-Boot reads from the iSCSI drive via the block IO protocol
offered by iPXE. It creates the partition handles and installs the simple file
-protocol. Now iPXE can call the simple file protocol to load Grub. U-Boot uses
-the block IO protocol offered by iPXE to fulfill the request.
-
-Once Grub is started it uses the same block IO protocol to load Linux. Via
-the EFI stub Linux is called as an EFI application.
-
-```
- +--------+ +--------+
- | | Runs | |
- | U-Boot |=========>| iPXE |
- | EFI | | snp.efi|
-+--------+ | | DHCP | |
-| |<====|********|<=========| |
-| DHCP | | | Get IP | |
-| Server | | | Address | |
-| |====>|********|=========>| |
-+--------+ | | Response | |
- | | | |
- | | | |
-+--------+ | | HTTPS | |
-| |<====|********|<=========| |
-| HTTPS | | | Load | |
-| Server | | | Script | |
-| |====>|********|=========>| |
-+--------+ | | | |
- | | | |
- | | | |
-+--------+ | | iSCSI | |
-| |<====|********|<=========| |
-| iSCSI | | | Auth | |
-| Server |====>|********|=========>| |
-| | | | | |
-| | | | Loads | |
-| |<====|********|<=========| | +--------+
-| | | | Grub | | Runs | |
-| |====>|********|=========>| |=======>| Grub |
-| | | | | | | |
-| | | | | | | |
-| | | | | | Loads | |
-| |<====|********|<=========|********|<=======| | +--------+
-| | | | | | Linux | | Runs | |
-| |====>|********|=========>|********|=======>| |=====>| Linux |
-| | | | | | | | | |
-+--------+ +--------+ +--------+ +--------+ | |
- | |
- | |
- | ~ ~ ~ ~|
-```
-
-## Security
+protocol. Now iPXE can call the simple file protocol to load GRUB[2]. U-Boot
+uses the block IO protocol offered by iPXE to fulfill the request.
+
+Once GRUB is started it uses the same block IO protocol to load Linux. Via
+the EFI stub Linux is called as an EFI application::
+
+ +--------+ +--------+
+ | | Runs | |
+ | U-Boot |========>| iPXE |
+ | EFI | | snp.efi|
+ +--------+ | | DHCP | |
+ | |<===|********|<========| |
+ | DHCP | | | Get IP | |
+ | Server | | | Address | |
+ | |===>|********|========>| |
+ +--------+ | | Response| |
+ | | | |
+ | | | |
+ +--------+ | | HTTPS | |
+ | |<===|********|<========| |
+ | HTTPS | | | Load | |
+ | Server | | | Script | |
+ | |===>|********|========>| |
+ +--------+ | | | |
+ | | | |
+ | | | |
+ +--------+ | | iSCSI | |
+ | |<===|********|<========| |
+ | iSCSI | | | Auth | |
+ | Server |===>|********|========>| |
+ | | | | | |
+ | | | | Loads | |
+ | |<===|********|<========| | +--------+
+ | | | | GRUB | | Runs | |
+ | |===>|********|========>| |======>| GRUB |
+ | | | | | | | |
+ | | | | | | | |
+ | | | | | | Loads | |
+ | |<===|********|<========|********|<======| | +--------+
+ | | | | | | Linux | | Runs | |
+ | |===>|********|========>|********|======>| |=====>| Linux |
+ | | | | | | | | | |
+ +--------+ +--------+ +--------+ +--------+ | |
+ | |
+ | |
+ | ~ ~ ~ ~|
+
+Security
+--------
The iSCSI protocol is not encrypted. The traffic could be secured using IPsec
but neither U-Boot nor iPXE does support this. So we should at least separate
the iSCSI traffic from all other network traffic. This can be achieved using a
virtual local area network (VLAN).
-## Configuration
+Configuration
+-------------
-### iPXE
+iPXE
+^^^^
-For running iPXE on arm64 the bin-arm64-efi/snp.efi build target is needed.
+For running iPXE on arm64 the bin-arm64-efi/snp.efi build target is needed::
git clone http://git.ipxe.org/ipxe.git
cd ipxe/src
@@ -132,7 +136,7 @@ http://ipxe.org/cfg
iPXE by default will put the CPU to rest when waiting for input. U-Boot does
not wake it up due to missing interrupt support. To avoid this behavior create
-file src/config/local/nap.h.
+file src/config/local/nap.h::
/* nap.h */
#undef NAP_EFIX86
@@ -140,7 +144,7 @@ file src/config/local/nap.h.
#define NAP_NULL
The supported commands in iPXE are controlled by an include, too. Putting the
-following into src/config/local/general.h is sufficient for most use cases.
+following into src/config/local/general.h is sufficient for most use cases::
/* general.h */
#define NSLOOKUP_CMD /* Name resolution command */
@@ -153,7 +157,9 @@ following into src/config/local/general.h is sufficient for most use cases.
#define DOWNLOAD_PROTO_NFS /* Network File System Protocol */
#define DOWNLOAD_PROTO_FILE /* Local file system access */
-## Links
+Links
+-----
-* https://ipxe.org - iPXE open source boot firmware
-* https://www.gnu.org/software/grub/ - GNU Grub (Grand Unified Bootloader)
+* [1](https://ipxe.org) https://ipxe.org - iPXE open source boot firmware
+* [2](https://www.gnu.org/software/grub/) https://www.gnu.org/software/grub/ -
+ GNU GRUB (Grand Unified Bootloader)
--
2.18.0
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