On 21/11/13 12:39, Grant Likely wrote:
> On Tue, 19 Nov 2013 12:58:12 +0000, James Hogan <[email protected]> 
> wrote:
>> Check whether initial_boot_params is NULL before dereferencing it in
>> unflatten_and_copy_device_tree() for the case where no device tree is
>> available but the arch can still boot to a minimal usable system without
>> it.
>>
>> Signed-off-by: James Hogan <[email protected]>
>> Cc: Grant Likely <[email protected]>
>> Cc: Rob Herring <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> ---
>>  drivers/of/fdt.c | 10 ++++++++--
>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>> index 2fa024b97c43..ac4983955e6d 100644
>> --- a/drivers/of/fdt.c
>> +++ b/drivers/of/fdt.c
>> @@ -922,8 +922,14 @@ void __init unflatten_device_tree(void)
>>   */
>>  void __init unflatten_and_copy_device_tree(void)
>>  {
>> -    int size = __be32_to_cpu(initial_boot_params->totalsize);
>> -    void *dt = early_init_dt_alloc_memory_arch(size,
>> +    int size;
>> +    void *dt;
>> +
>> +    if (!initial_boot_params)
>> +            return;
> 
> Worth logging a message for those who can obtain the kernel log
> buffer?

Yes, sounds reasonable (especially since for Meta the platform name detected 
from DT doesn't get logged in this case and I still get the console out via 
JTAG probe).
I'll post a v2 adding this:

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index ac4983955e6d..758b4f8b30b7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -925,8 +925,10 @@ void __init unflatten_and_copy_device_tree(void)
        int size;
        void *dt;
 
-       if (!initial_boot_params)
+       if (!initial_boot_params) {
+               pr_warn("No valid device tree found, continuing without\n");
                return;
+       }
 
        size = __be32_to_cpu(initial_boot_params->totalsize);
        dt = early_init_dt_alloc_memory_arch(size,

> Otherwise:
> 
> Acked-by: Grant Likely <[email protected]>

Thanks
James

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