On Tue, Nov 25, 2014 at 8:37 AM, Grant Likely <grant.likely@xxxxxxxxxx> wrote:
> On Tue, 25 Nov 2014 12:54:55 +0000
> , Ian Campbell <ian.campbell@xxxxxxxxxx>
> wrote:
>> memblock_is_region_reserved() returns true in the case of a partial
>> overlap, meaning that the current code fails to reserve the
>> non-overlapping portion.
>>
>> I observed this causing a Midway system with a buggy fdt (the header
>> declares itself to be larger than it really is) failing to boot
>> because the over-inflated size of the fdt was causing it to seem to
>> run into the swapper_pg_dir region, meaning the DT wasn't reserved.
>> The symptoms were failing to find an disks or network and failing to
>> boot. I think it is work printing a warning in this case.
>>
>> However given the ambiguity of whether things like the initrd are
>> covered by /memreserve/ and similar I think it is best to also
>> register the region rather than just ignoring it.
>>
>> Since memblock_reserve() handles overlaps just fine lets just warn and
>> carry on.
>>
>> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
>> Cc: Grant Likely <grant.likely@xxxxxxxxxx>
>> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
>> Cc: devicetree@xxxxxxxxxxxxxxx
>> ---
>> drivers/of/fdt.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>> index 30e97bc..4f0f24c 100644
>> --- a/drivers/of/fdt.c
>> +++ b/drivers/of/fdt.c
>> @@ -965,7 +965,8 @@ int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
>> phys_addr_t size, bool nomap)
>> {
>> if (memblock_is_region_reserved(base, size))
>> - return -EBUSY;
>> + pr_warning("DT reserved region at 0x%pa is already reserved\n",
>> + &base);
>
> Since memblock_remove/reserve does the right thing anyway, let's just
> drop the test entirely.
If the region completely overlaps, then I agree it is okay to be
quiet. But if we have partially overlapping region already with the
dtb, then we should warn here. We want to know if someone passes a dtb
that is too big.
Rob
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