Visible to Intel only — GUID: sfo1410067744653
Ixiasoft
Visible to Intel only — GUID: sfo1410067744653
Ixiasoft
4.1.2. Security Reset Functions
When secure mode is enabled on the device, reset manager performs some additional functions. To avoid unsecure snooping of existing RAM contents, the HPS can be configured to clear all RAM, both general-purpose RAM and dedicated RAM that is integrated into modules. The list of RAMs on the HPS is:
- Onchip RAM
- USB0
- USB1
- SDMMC
- EMAC0 - EMAC2 RX and TX buffers
- DMA
- NAND Read, Write and ECC RAMs
- QSPI
- MPU RAM
RAMs can be cleared on cold reset, warm reset or both as there are separate fuses that control behavior for cold and warm resets. When the corresponding fuse is blown, all RAMs are cleared for the indicated reset type. If an additional fuse is blown, the various RAM contents are cleared sequentially; otherwise, the contents of all of the RAMs are cleared simultaneously. Even if all security RAM clearing is disabled, the reset manager always invalidates the MPU L1 Cache.
The HPS also supports an Anti-Tamper interface from the FPGA fabric to security manager. If an Anti-Tamper event occurs, the HPS clears all RAMs and becomes unresponsive. The HPS only recovers from this state by a POR. Anti-Tamper logic, such as voltage detection, may reside in the FPGA.