Increase the RAM size to 1 MB for debugging

[jthornblad]

Description

When making TKey apps that need a lot of debugging information and be build with -O0 optimization, the binary size can greatly exceed what the final optimized binary size will be.

To be able to debug in an efficient manner, increase the emulated RAM to 1 MB.

Type of change

Please tick any that are relevant to this PR and remove any that aren't.

• Bugfix (non breaking change which resolve an issue)
• Feature (non breaking change which adds functionality)
• Breaking Change (a change which would cause existing functionality to not work as expected)
• Documentation (a change to documentation)

Submission checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my changes
• I have tested and verified my changes on target
• My changes are well written and CI is passing
• I have squashed my work to relevant commits and rebased on main for linear history
• I have added a "Co-authored-by: x" if several people contributed, either pair programming or by squashing commits from different authors.
• I have updated the documentation where relevant (readme, dev.tillitis.se etc.)
• QEMU is updated to reflect changes

[mchack-work]

How about making the RAM configurable by some command line argument? Maybe just differentiate between the real thing and debug mode, or possible being able to set the exact amount of RAM?

[agren]

Having 128k as default, and increase the RAM size when needed seems like the least surprising behavior to me.

To set an arbitrary RAM size we could probably use the existing -m flag (configure guest RAM). When I try to run QEmu with 1 MiB RAM:

qemu-system-riscv32 -m 1M -nographic -M tk1-castor,fifo=chrid -bios qemu_firmware.elf -chardev pty,id=chrid -s -d guest_errors -drive file=flash.bin,if=mtd,format=raw,index=0

I get the following error:

qemu-system-riscv32: Invalid RAM size, should be 128 KiB.

Which comes from a check in tk1.c. It might be as easy as removing the check to get configurable size.