Clarify EL3 payload documentation
This patch reworks the section about booting an EL3 payload in the User Guide: - Centralize all EL3 payload related information in the same section. - Mention the possibility to program the EL3 payload in flash memory and execute it in place. - Provide model parameters for both the Base and Foundation FVPs. - Provide some guidance to boot an EL3 payload on Juno. Change-Id: I975c8de6b9b54ff4de01a1154cba63271d709912
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@ -859,6 +859,84 @@ flow. In particular:
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* MMU disabled;
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* Caches disabled.
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### Booting an EL3 payload
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The EL3 payload image is a standalone image and is not part of the FIP. It is
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not loaded by the Trusted Firmware. Therefore, there are 2 possible scenarios:
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* The EL3 payload may reside in non-volatile memory (NVM) and execute in
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place. In this case, booting it is just a matter of specifying the right
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address in NVM through `EL3_PAYLOAD_BASE` when building the TF.
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* The EL3 payload needs to be loaded in volatile memory (e.g. DRAM) at
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run-time.
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To help in the latter scenario, the `SPIN_ON_BL1_EXIT=1` build option can be
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used. The infinite loop that it introduces in BL1 stops execution at the right
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moment for a debugger to take control of the target and load the payload (for
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example, over JTAG).
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It is expected that this loading method will work in most cases, as a debugger
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connection is usually available in a pre-production system. The user is free to
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use any other platform-specific mechanism to load the EL3 payload, though.
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#### Booting an EL3 payload on FVP
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The EL3 payloads boot flow requires the CPU's mailbox to be cleared at reset for
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the secondary CPUs holding pen to work properly. Unfortunately, its reset value
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is undefined on the FVP platform and the FVP platform code doesn't clear it.
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Therefore, one must modify the way the model is normally invoked in order to
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clear the mailbox at start-up.
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One way to do that is to create an 8-byte file containing all zero bytes using
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the following command:
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dd if=/dev/zero of=mailbox.dat bs=1 count=8
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and pre-load it into the FVP memory at the mailbox address (i.e. `0x04000000`)
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using the following model parameters:
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--data cluster0.cpu0=mailbox.dat@0x04000000 [Base FVPs]
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--data=mailbox.dat@0x04000000 [Foundation FVP]
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To provide the model with the EL3 payload image, the following methods may be
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used:
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1. If the EL3 payload is able to execute in place, it may be programmed into
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flash memory. On Base Cortex and AEM FVPs, the following model parameter
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loads it at the base address of the NOR FLASH1 (the NOR FLASH0 is already
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used for the FIP):
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-C bp.flashloader1.fname="/path/to/el3-payload"
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On Foundation FVP, there is no flash loader component and the EL3 payload
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may be programmed anywhere in flash using method 3 below.
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2. When using the `SPIN_ON_BL1_EXIT=1` loading method, the following DS-5
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command may be used to load the EL3 payload ELF image over JTAG:
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load /path/to/el3-payload.elf
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3. The EL3 payload may be pre-loaded in volatile memory using the following
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model parameters:
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--data cluster0.cpu0="/path/to/el3-payload"@address [Base FVPs]
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--data="/path/to/el3-payload"@address [Foundation FVP]
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The address provided to the FVP must match the `EL3_PAYLOAD_BASE` address
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used when building the Trusted Firmware.
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#### Booting an EL3 payload on Juno
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If the EL3 payload is able to execute in place, it may be programmed in flash
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memory by adding an entry in the `SITE1/HBI0262x/images.txt` configuration file
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on the Juno SD card (where `x` depends on the revision of the Juno board).
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Refer to the [Juno Getting Started Guide], section 2.3 "Flash memory
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programming" for more information.
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Alternatively, the same DS-5 command mentioned in the FVP section above can
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be used to load the EL3 payload's ELF file over JTAG on Juno.
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8. Preparing the images to run on FVP
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--------------------------------------
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@ -1211,38 +1289,6 @@ The `bp.variant` parameter corresponds to the build variant field of the
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`SYS_ID` register. Setting this to `0x0` allows the ARM Trusted Firmware to
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detect the legacy VE memory map while configuring the GIC.
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### Booting an EL3 payload on FVP
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Booting an EL3 payload on FVP requires a couple of changes to the way the
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model is normally invoked.
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First of all, the EL3 payload image is not part of the FIP and is not loaded by
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the Trusted Firmware. Therefore, it must be loaded in memory some other way.
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There are 2 ways of doing that:
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1. It can be loaded over JTAG at the appropriate time. The infinite loop
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introduced in BL1 when compiling the Trusted Firmware with
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`SPIN_ON_BL1_EXIT=1` stops execution at the right moment for a debugger to
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take control of the target and load the payload.
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2. It can be pre-loaded in the FVP memory using the following model parameter:
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--data="<path-to-binary>"@<base-address-of-binary>
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The base address provided to the FVP must match the `EL3_PAYLOAD_BASE`
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address used when building the Trusted Firmware.
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Secondly, the EL3 payloads boot flow requires the CPUs mailbox to be cleared
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at reset for the secondary CPUs holding pen to work properly. Unfortunately,
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its reset value is undefined on FVP. One way to clear it is to create an
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8-byte file containing all zero bytes and pre-load it into the FVP memory at the
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mailbox address (i.e. `0x04000000`) using the same `--data` FVP parameter as
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described above.
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The following command creates such a file called `mailbox.dat`:
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dd if=/dev/zero of=mailbox.dat bs=1 count=8
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10. Running the software on Juno
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---------------------------------
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@ -1344,7 +1390,7 @@ used to test the GICv3 kernel on the respective FVP models.
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- - - - - - - - - - - - - - - - - - - - - - - - - -
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_Copyright (c) 2013-2015, ARM Limited and Contributors. All rights reserved._
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_Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved._
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[Firmware Design]: firmware-design.md
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