[PATCH v3 6/6] doc: uefi: Describe UEFI HTTPs boot

[Ilias Apalodimas]

We now can use a combination og lwIP & mbedTLS and download from
https://. Describe the config options needed to enable it as well
as some limitations

Reviewed-by: Simon Glass <sjg at chromium.org>
Reviewed-by: Jerome Forissier <jerome.forissier at linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
 doc/develop/uefi/uefi.rst | 45 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst
index 0760ca91d4fc..48d6110b2ad1 100644
--- a/doc/develop/uefi/uefi.rst
+++ b/doc/develop/uefi/uefi.rst
@@ -681,8 +681,8 @@ UEFI variables. Booting according to these variables is possible via::
 As of U-Boot v2020.10 UEFI variables cannot be set at runtime. The U-Boot
 command 'efidebug' can be used to set the variables.
 
-UEFI HTTP Boot
-~~~~~~~~~~~~~~
+UEFI HTTP Boot using the legacy TCP stack
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 HTTP Boot provides the capability for system deployment and configuration
 over the network. HTTP Boot can be activated by specifying::
@@ -715,6 +715,47 @@ We need to preset the "httpserverip" environment variable to proceed the wget::
 
     setenv httpserverip 192.168.1.1
 
+UEFI HTTP(s) Boot using lwIP
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Similar to the above U-Boot can do EFI HTTP boot using lwIP. If we combine this
+with Mbed TLS we can also download from https://
+
+HTTP(s) Boot can be activated by specifying::
+
+    CONFIG_EFI_HTTP_BOOT
+    CONFIG_NET_LWIP
+    CONFIG_WGET_HTTPS
+
+For QEMU targets there's a Kconfig that supports this by default::
+
+    make qemu_arm64_lwip_defconfig
+
+The commands and functionality are similar to the legacy stack, with the notable
+exception of not having to define an "httpserverip" if you are trying to resolve
+an IP. However, lwIP code doesn't yet support redirects::
+
+    => efidebug boot add -u 1 netinst https://cdimage.debian.org/cdimage/weekly-builds/arm64/iso-cd/debian-testing-arm64-netinst.iso
+    => dhcp
+    DHCP client bound to address 10.0.2.15 (3 ms)
+    => efidebug boot order 1
+    => bootefi bootmgr
+
+    HTTP server error 302
+    Loading Boot0001 'netinst' failed
+    EFI boot manager: Cannot load any image
+
+If the url you specified isn't a redirect::
+
+    => efidebug boot add -u 1 netinst https://download.rockylinux.org/pub/rocky/9/isos/aarch64/Rocky-9.4-aarch64-minimal.iso
+    => dhcp
+    => bootefi bootmgr
+    #######################################
+
+If the downloaded file extension is .iso or .img file, efibootmgr tries to
+mount the image and boot with the default file(e.g. EFI/BOOT/BOOTAA64.EFI).
+If the downloaded file is PE-COFF image, load the downloaded file and
+start it.
+
 Executing the built in hello world application
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-- 
2.43.0