Re: [PATCH v7 2/2] arm64: boot: Support Flat Image Tree

Hi,

a few more comments after decompiling the FIT image:

On 29.11.23 18:21, Simon Glass wrote:

+    with fsw.add_node('kernel'):
+        fsw.property_string('description', args.name)
+        fsw.property_string('type', 'kernel_noload')

The specification only says no loading done, but doesn't explain what it
means for a bootloader to _not_ load an image. Looking into the U-Boot commit
b9b50e89d317 ("image: Implement IH_TYPE_KERNEL_NOLOAD") that introduces this,
apparently no loading means ignoring load and entry address?

I presume missing load and entry is something older U-Boot versions
were unhappy about? Please let me know if the semantics are as I understood,
so I can prepare a barebox patch supporting it.

+        fsw.property_string('arch', args.arch)
+        fsw.property_string('os', args.os)
+        fsw.property_string('compression', args.compress)
+        fsw.property('data', data)
+        fsw.property_u32('load', 0)
+        fsw.property_u32('entry', 0)
+
+
+def finish_fit(fsw, entries):
+    """Finish the FIT ready for use
+
+    Writes the /configurations node and subnodes
+
+    Args:
+        fsw (libfdt.FdtSw): Object to use for writing
+        entries (list of tuple): List of configurations:
+            str: Description of model
+            str: Compatible stringlist
+    """
+    fsw.end_node()
+    seq = 0
+    with fsw.add_node('configurations'):
+        for model, compat in entries:
+            seq += 1
+            with fsw.add_node(f'conf-{seq}'):
+                fsw.property('compatible', bytes(compat))

The specification says that this is the root U-Boot compatible,
which I presume to mean the top-level compatible, which makes sense to me.

The code here though adds all compatible strings from the device tree though,
is this intended?

+        fsw.property_string('description', model)
+        fsw.property_string('type', 'flat_dt')
+        fsw.property_string('arch', arch)
+        fsw.property_string('compression', compress)
+        fsw.property('compatible', bytes(compat))

I think I've never seen a compatible for a fdt node before.
What use does this serve?

Cheers,
Ahmad

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