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    ARM: BCM5301X: workaround suppress fault · fdf4850c
    Hauke Mehrtens 提交于
    Without this patch I am getting a unhandled fault exception like this
    one after "Freeing unused kernel memory":
    
    Freeing unused kernel memory: 1260K (c02c1000 - c03fc000)
    Unhandled fault: imprecise external abort (0x1c06) at 0xb6f89005
    Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007
    
    The address which is here 0xb6f89005 changes from boot to boot, with a
    new build the changes are bigger. With kernel 3.10 I have also seen
    this fault at different places in the boot process, but starting with
    3.11 they are always occurring after the "Freeing unused kernel memory"
    message. I never was able to completely boot to userspace without this
    handler. The abort code is constant 0x1c06. This fault just happens
    once in the boot process I have never seen it happing twice or more.
    
    I also tried changing the CPSR.A bit to 0 in init_early, with this code
    like Afzal suggested, but that did not change anything:
    asm volatile("mrs r12, cpsr\n"
    	"bic r12, r12, #0x00000100\n"
    	"msr cpsr_c, r12" ::: "r12", "cc", "memory");
    
    Disabling the L2 cache by building with CONFIG_CACHE_L2X0 unset did not
    help.
    
    This workaround was copied from the vendor code including most of the
    comments. It says it they think this is caused by the CFE boot loader
    used on this device. I do not have any access to any datasheet or
    errata document to check this.
    Signed-off-by: NHauke Mehrtens <hauke@hauke-m.de>
    Acked-by: NArnd Bergmann <arnd@arndb.de>
    Acked-by: NChristian Daudt <bcm@fixthebug.org>
    Signed-off-by: NMatt Porter <mporter@linaro.org>
    fdf4850c
bcm_5301x.c 1.4 KB