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fw: Clarify and correct doc

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Michael Cardell Widerkrantz 2022-11-03 16:11:31 +01:00
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commit 254a384181
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2 changed files with 7 additions and 6 deletions
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3
README.md
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@ -20,7 +20,8 @@ ensuring that each app loaded will have its own cryptographic
identity. The design is similar to TCG DICE. The Tillitis Key 1
platform has 128 KB of RAM. The current firmware is designed to load
an app that is up to 100 KB in size, and gives it a stack of 28 KB. A
smaller ap may move itself in memory, in order to have a larger stack.
smaller app may want to move itself in memory to get larger continuous
memory.
![Tillitis Key 1 PCB, first implementation](doc/images/mta1-usb-v1.jpg)
*Tillitis Key 1 PCB, first implementation*

10
doc/system_description/software.md
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@ -64,8 +64,8 @@ between the host and the device.
The device has 128 KB RAM. The current firmware loads the app at the
upper 100 KB. The lower 28 KB is set up as stack for the app. A
smaller app that wants a larger stack could relocate itself on
startup.
smaller app that wants continuous memory may want to relocate itself
when starting.
The firmware is part of FPGA bitstream (ROM), and is loaded at
`0x0000_0000`.
@ -83,7 +83,7 @@ read, the firmware executes the command.
### Loading an application
The purpose of the firmware is to bootstrap an application. The host
will send a raw binary targeted to be loaded at `0x4001_0000` in the
will send a raw binary targeted to be loaded at `0x4000_7000` in the
device.
1. The host sends the User Supplied Secret (USS) by using the
@ -98,7 +98,7 @@ device.
multiple `FW_CMD_LOAD_APP_DATA` commands, together containing the
full application.
5. For each received `FW_CMD_LOAD_APP_DATA` command the firmware
places the data into `0x4001_0000` and upwards. The firmware
places the data into `0x4000_7000` and upwards. The firmware
replies with a `FW_RSP_LOAD_APP_DATA` response to the host for
each received block.
6. When the final block of the application image is received, we
@ -107,7 +107,7 @@ device.
The Compound Device Identifier is computed by using the `UDS`,
the measurement of the application, and the `USS`, and placed in
the `CDI` register. Then `0x4001_0000` is written to `APP_ADDR`.
the `CDI` register. Then `0x4000_7000` is written to `APP_ADDR`.
The final `FW_RSP_LOAD_APP_DATA` response is sent to the host,
completing the loading.