[Qemu-arm] Custom machine: Forcing initial boot address

[Bensch, Alexander]

Sensitive / Proprietary

Hello all,

I am currently trying to modify the MPS2 board to emulate an ARMv7m device I am working on, as none of the included machines provide an environment close enough to what I’m working on to be sufficient. I am running into an issue in which I cannot get the machine to execute the bootROM from address 0xFFFF0000. The specs for the specific device I have (cannot share the device model, unfortunately) state that there is a control register that I assume is present in all v7m chips that selects whether to boot at 0x0 or 0xFFFF0000. I can also see evidence of this register being emulated in QEMU in ‘target/arm/cpu.c’. However, since there is little API documentation I have been able to find, I’ve effectively been reverse-engineering QEMU to figure out what needs to be set. So far, all of my attempts to modify control registers and addresses directly have resulted in unexpected behavior and partial implementation of my goals. I have had success in forcing the ROM to load at the desired address, and with GDB I can force the PC and SP to where I want, but the IVT must be at 0x0 by default. I was hoping someone knew how to enable the control register that sets the boot address so that the IVT can be loaded from a different address.

I am running QEMU version 2.11.

 

Apologies if this is the wrong place or not the expected format. I haven’t used a mailing list before and I couldn’t find any guidelines or etiquette rules.

Thanks!

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