REFACTOR: change bootaddr register address and PC reset vector address

[T-K-233]

Go along with PR in testchipip #196

The motivation is that the current organization of the bootrom code and the reset vector is rather confusing. One would normally assume that the reset vector is pointed toward the base of a memory section (e.g. 0x10000).

This could also benefit future bootrom code development.

The boot-up sequence of the SoC would now be:

PC resets at address 0x00010000, and reads from the BootROM code. Within the BootROM code, the hart will read from BOOTSEL register, which is controlled by a external boot select pin, located at 0x00001000 on the memory map, to determine the following boot sequence.

Related PRs / Issues:

Type of change:

• Bug fix
• New feature
• Other enhancement

Impact:

• RTL change
• Software change (RISC-V software)
• Build system change
• Other

Contributor Checklist:

• Did you set main as the base branch?
• Is this PR's title suitable for inclusion in the changelog and have you added a changelog:<topic> label?
• Did you state the type-of-change/impact?
• Did you delete any extraneous prints/debugging code?
• Did you mark the PR with a changelog: label?
• (If applicable) Did you update the conda .conda-lock.yml file if you updated the conda requirements file?
• (If applicable) Did you add documentation for the feature?
• (If applicable) Did you add a test demonstrating the PR?

• (If applicable) Did you mark the PR as Please Backport?

[jerryz123]

I found the bug, check my comment in your testchipip PR.

Can you also update the docs references to 0x10040? After that this should be fine

[jerryz123]

Thanks for seeing this through @T-K-233 .
@abejgonzalez any opposition? I think we've checked all the boxes for this major change.

If there is no opposition, I can fix the remaining merge conflict, and merge this.

[abejgonzalez]

SFTM. I do like the change to always start at 0x10000 and go up from there.