[PATCH v2] sandbox: Fix VPL instructions

[Simon Glass]

Fix the devicetree used with sandbox. This is needed because the
default (full) devicetree must be used by all phases of boot, with
sandbox.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

Changes in v2:
- Assume a build in the source directory
- Add a trace of it running
- Add explicit build instructions

 doc/arch/sandbox/sandbox.rst | 50 +++++++++++++++++++++++++++++++++---
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/doc/arch/sandbox/sandbox.rst b/doc/arch/sandbox/sandbox.rst
index 23902dee89e7..5f8db126657f 100644
--- a/doc/arch/sandbox/sandbox.rst
+++ b/doc/arch/sandbox/sandbox.rst
@@ -424,15 +424,59 @@ space. See existing code for examples.
 VPL (Verifying Program Loader)
 ------------------------------
 
-Sandbox provides an example build of vpl called `sandbox_vpl`. This can be run
-using::
+Sandbox provides an example build of vpl called `sandbox_vpl`. To build it:
 
-   /path/to/sandbox_vpl/tpl/u-boot-tpl -D
+.. code-block:: bash
+
+   make sandbox_vpl_defconfig all
+
+This can be run using:
+
+.. code-block:: bash
+
+   ./tpl/u-boot-tpl -d u-boot.dtb
 
 It starts up TPL (first-stage init), then VPL, then runs SPL and finally U-Boot
 proper, following the normal flow for a verified boot. At present, no
 verification is actually implemented.
 
+Here is an example trace::
+
+   U-Boot TPL 2024.01-rc2-00129 (Nov 19 2023 - 08:10:12 -0700)
+   Trying to boot from sandbox_image
+   Trying to boot from sandbox_file
+
+   U-Boot VPL 2024.01-rc2-00129 (Nov 19 2023 - 08:10:12 -0700)
+   Trying to boot from vbe_simple
+   Trying to boot from sandbox_image
+   Trying to boot from sandbox_file
+
+   U-Boot SPL 2024.01-rc2-00129 (Nov 19 2023 - 08:10:12 -0700)
+   Trying to boot from vbe_simple
+   Trying to boot from sandbox_image
+   Trying to boot from sandbox_file
+
+
+   U-Boot 2024.01-rc2-00129 (Nov 19 2023 - 08:10:12 -0700)
+
+   Reset Status: COLD
+   Model: sandbox
+   DRAM:  256 MiB
+   using memory 0x1b576000-0x1f578000 for malloc()
+
+   Warning: host_lo MAC addresses don't match:
+   Address in ROM is		96:cd:ef:82:78:51
+   Address in environment is	02:00:11:22:33:44
+   Core:  103 devices, 51 uclasses, devicetree: board
+   MMC:
+   Loading Environment from nowhere... OK
+   In:    serial,cros-ec-keyb,usbkbd
+   Out:   serial,vidconsole
+   Err:   serial,vidconsole
+   Model: sandbox
+   Net:   eth0: host_lo, eth1: host_enp14s0, eth2: host_eth6, eth3: host_wlp15s0, eth4: host_virbr0, eth5: host_docker0, eth6: eth at 10002000
+   Hit any key to stop autoboot:  1
+
 
 Debugging the init sequence
 ---------------------------
-- 
2.43.0.rc0.421.g78406f8d94-goog