The APPSBL and anything after that it not allowed to touch some of the
memory regions which are used by other components. Still trying to write to
the memory can lead to sudden device restarts
(IPQ40xx) # mw 87e80000 0
data abort
pc : [<873149f8>] lr : [<87308578>]
sp : 86edfc28 ip : 86ef4412 fp : 00000000
r10: 00000000 r9 : 00000000 r8 : 86edff68
r7 : 00000003 r6 : 8737e624 r5 : 86ef4420 r4 : 8736c154
r3 : 00000000 r2 : 00000010 r1 : 00000000 r0 : 00000000
Flags: nZCv IRQs off FIQs off Mode SVC_32
Resetting CPU ...
The device manufacturer only provided a very rough list of regions:
* rsvd1: 0x87000000 0x500000
* wifi_dump: 0x87500000 0x600000
* rsvd2: 0x87b00000 0x500000
A more detailed list for devices using the AP.DK reference design memory
maps was provided by Roman Yeryomin <roman@advem.lv> in commit 56f2df879fd
("ipq806x: ipq4019: add ap-dk01.1-c1 board support"):
* apps_bl: 0x87000000 0x400000
* sbl: 0x87400000 0x100000
* cnss_debug: 0x87500000 0x600000
* cpu_context_dump: 0x87b00000 0x080000
* tz_apps: 0x87b80000 0x280000
* smem: 0x87e00000 0x080000
* tz: 0x87e80000 0x180000
The u-boot function ipq_fdt_mem_rsvd_fixup seems to suggest that only the
rsvd2 (tz_apps, smem, tz) should be protected. All other regions would have
been removed by it when CONFIG_QCA_APPSBL_DLOAD is not enabled. This allows
to reduce the 16MB reserved memory region to only 4.5MB.
Signed-off-by: Sven Eckelmann <sven.eckelmann@openmesh.com>
7004f681cd