Enabling CPU_DCACHE_DISABLE on a SMP capable system will prevent the
kernel from booting because of the following ldrex instruction in
arch_spin_lock:
(gdb) x/10i $pc
=> 0xc053cfa8 <_raw_spin_lock+4>: ldrex r3, [r0]
0xc053cfac <_raw_spin_lock+8>: add r2, r3, #65536 ; 0x10000
which is taken by the very first printk call:
at /home/fainelli/work/linux/arch/arm/include/asm/spinlock.h:65
fmt=0xc0637650 " 01 66Booting Linux on physical CPU 0x%xn", args=<incomplete type>)
at kernel/printk/printk.c:1525
fmt=0xc05370f4 <printk+52> " 24320215342 04340235344 20320215342 36377/341 17") at kernel/printk/printk.c:1688
ldrex requires exclusive monitor(s) (local or global) which are no longer
working when the Data cache is disabled in CP15 and will just hang the CPU
there.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
e1e2f6e4c5