[riot-notifications] [RIOT-OS/RIOT] riotboot/Makefile.include: increase RIOTBOOT_HRD_LEN for ARMv7*-M (#11641)

Gaëtan Harter notifications at github.com
Mon Jun 17 14:15:21 CEST 2019


cladmi commented on this pull request.

Some wording remarks, plus would like to have the link to the datasheet.
It would allow updating it later for new architecture and have all the context for justifying the values.

As it is CPU specific, its good to put the maximum possible required value by default.

> @@ -1,7 +1,15 @@
-# Indicate the reserved space for a header, 256B by default
-# Notice that it must be 256B aligned. This is restricted by
-# the Cortex-M0+/3/4/7 architecture
-RIOTBOOT_HDR_LEN ?= 0x100
+# Indicate the reserved space for a header.
+# Notice that it must be at least 256B aligned. This is restricted by

Could you update to remove the previous `Notice that it must be at least 256 aligned` and include this part in the following part. Currently it has two different informations mixed.

> @@ -1,7 +1,15 @@
-# Indicate the reserved space for a header, 256B by default
-# Notice that it must be 256B aligned. This is restricted by
-# the Cortex-M0+/3/4/7 architecture
-RIOTBOOT_HDR_LEN ?= 0x100
+# Indicate the reserved space for a header.
+# Notice that it must be at least 256B aligned. This is restricted by
+# the Cortex-M0+/3/4/7 architecture. "The Vector table must be naturally
+# aligned to a power of two whose alignment value is greater than or equal
+# to number of Exceptions supported x 4"

It would be good if you have a link for this information, it would be useful for porting future boards and justifying the values.

> @@ -1,7 +1,15 @@
-# Indicate the reserved space for a header, 256B by default
-# Notice that it must be 256B aligned. This is restricted by
-# the Cortex-M0+/3/4/7 architecture
-RIOTBOOT_HDR_LEN ?= 0x100
+# Indicate the reserved space for a header.
+# Notice that it must be at least 256B aligned. This is restricted by
+# the Cortex-M0+/3/4/7 architecture. "The Vector table must be naturally
+# aligned to a power of two whose alignment value is greater than or equal
+# to number of Exceptions supported x 4"
+# For ARMv7-M/ARMv7E-M (M4, M3, M7). Maximum of 256 exceptions (256*4 bytes == 0x400).

You can put it as markdown style items with `# * lalala`

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