Add support for Implied ApobNvCopy BHD directory entry

[citrus-it]

In order to support eMCR - https://github.com/oxidecomputer/stlouis/issues/707

The flash address here is a placeholder, but it looks like the right thing was done:

atrium:helios:emcr% gmake turin-rubyred-1.0.0.2-p1.img PAYLOAD=../nanobl-rs/obj/nanobl-rs.elf
cargo run -- generate -s '16 MiB'  -v -B . -B amd-firmware/BRH/1.0.0.2-p1 -c etc/turin-rubyred-1.0.0.2-p1.efs.json5 -r ../nanobl-rs/obj/nanobl-rs.elf -o turin-rubyred-1.0.0.2-p1.img
    Finished dev [unoptimized + debuginfo] target(s) in 0.06s
     Running `target/debug/amd-host-image-builder generate -s '16 MiB' -v -B . -B amd-firmware/BRH/1.0.0.2-p1 -c etc/turin-rubyred-1.0.0.2-p1.efs.json5 -r ../nanobl-rs/obj/nanobl-rs.elf -o turin-rubyred-1.0.0.2-p1.img`

atrium:helios:emcr% cargo run dump -i turin-rubyred-1.0.0.2-p1.img | grep -B3 -A13 Apob
    Finished dev [unoptimized + debuginfo] target(s) in 0.06s
     Running `target/debug/amd-host-image-builder dump -i turin-rubyred-1.0.0.2-p1.img`
        {
          source: "Implied",
          target: {
            type: "Apob",
            region_type: "Normal",
            reset_image: false,
            copy_image: false,
            read_only: false,
            compressed: false,
            instance: 0,
            sub_program: 0,
            rom_id: "SpiCs1",
            flash_location: 0,
            size: 0,
            ram_destination_address: 67108864
          }
        },
        {
          source: "Implied",
          target: {
            type: "ApobNvCopy",
            region_type: "Normal",
            reset_image: false,
            copy_image: false,
            read_only: false,
            compressed: false,
            instance: 0,
            sub_program: 0,
            rom_id: "SpiCs1",
            flash_location: 305419896,
            size: 851968,
            ram_destination_address: null
          }
        },

[daym]

That flash_location seems to be about 291 MiB ? Uhh.

There's a limitation of my flash allocator as it is currently used: It can't do custom reserved ranges (but it can do reserved ranges in general and there is one used).

Therefore, specifying flash_location like that is not safe (except when you specify it for all items and for all the directories themselves--which is possible even in the json5 file!). The allocator will not exclude any explicitly specified flash_location .. (flash_location + size) range from the range it can allocate from in the future.

Are you sure that specifying flash_location like this is even required?

It might be that the allocator allocates anyway if you don't specify flash_location and don't specify a Blob source either--or could be easily be made to do that.

We should definitely add a test for that case now that we need it, though.

Or, the hacky solution would be since we only use 16 MiB of the flash anyway, set flash_location to above 16 MiB. Let's not do that, though.

[citrus-it]

For eMCR our plan was to add an ApobNvCopy entry that points to 64MiB which is a location in flash that's separately managed by the SP and should contain a cached copy of the APOB from the last boot.

The value in this draft PR is just a placeholder.
Because we currently need to apply an offset for flash access from the host on RubyRed (of 0x3000000), I have been using

                    flash_location: 0x7000000,

for testing. However, the ABL (specifically the PMU eMCR firmware) ends up trying to read from address 0x0 so it is either unhappy with this, or not finding it because I did not place it in the second level directory, and I think I may need to.

[daym]

I see!

There is pretty complete second level directory support in amd-host-image-builder by now--so we can try it with that.

[citrus-it]

Yes, this is compiling, but the PSP doesn't seem to boot. I suspect I need to put more items in there like one of the stock ROMs.

+        {
+          source: {
+            SecondLevelDirectory: {
+              entries: [
+                {
+                  "source": "Implied",
+                  "target": {
+                    "type": "Apob",
+                    "ram_destination_address": 0x4000000
+                  }
+                },
+                {
+                  "source": "Implied",
+                  target: {
+                    type: "ApobNvCopy",
+                    flash_location: 0x7000000,
+                    size: 0xd0000
+                  }
+                }
+              ]
+            }
+          },
+          target: {
+            type: "SecondLevelDirectory"
+          }
+        },