How to configure platform.regions.base & size for risc32?

[yangn0]

Hi,

I'm trying to build bao for riscv32.

But I encountered a strange problem.

It always prints ERROR here.

reg->base + reg->size should be set to the total region of bao+vm, right?

If I try to reduce the region, another error appears:

this function will return a null.

[yangn0]

Should VMs be placed before or after the hypervisor?

[josecm]

This seems to be related to a limitation Bao has on 32-bit platforms due to the physical address space being too small. BAO_VAS_BASE defines the base virtual address to which Bao maps its image and other structures. On RISC-V bao needs to identity map all the platform memory regions, the main reason being allowing for page-table walks. If one of this regions physical address coincides with the region bao uses for its virtual addresses this map fails.

I am sorry to say we don't have a solution for this issue at the moment. But we can try to think of some workaround. Could you please tell us which is your target plartorm and provide the platform description file you are using for Bao?

[yangn0]

Hi,
Thanks for your detailed reply.

I have solved this problem. I mistakenly loaded bao into the location 0xc0000000, which is the entry point of this elf. After reading boot.s, I found that it has a PIC code. I tried loading it at 0x80400000. it works!

And there is another question:

The s6 is the size of VM. Why the _page_tables_start and _page_tables_end offset s6 size?