Re: [PATCH] ARM: zynq: Reserve correct amount of non-DMA RAM

[Nathan Rossi]

On 10 November 2016 at 19:33, Nathan Rossi <nathan@xxxxxxxxxxxxxxx> wrote:
> On 10 November 2016 at 18:41, Michal Simek <monstr@xxxxxxxxx> wrote:
>> + Nathan
>>
>> 2016-10-31 17:26 GMT+01:00 Kyle Roeschley <kyle.roeschley@xxxxxx>:
>>>
>>> On Zynq, we haven't been reserving the correct amount of DMA-incapable
>>> RAM to keep DMA away from it (per the Zynq TRM Section 4.1, it should be
>>> the first 512k). In older kernels, this was masked by the
>>> memblock_reserve call in arm_memblock_init(). Now, reserve the correct
>>> amount excplicitly rather than relying on swapper_pg_dir, which is an
>>> address and not a size anyway.
>>>
>>> Fixes: 46f5b96 ("ARM: zynq: Reserve not DMAable space in front of the
>>> kernel")
>>>
>>> Signed-off-by: Kyle Roeschley <kyle.roeschley@xxxxxx>
>
> Tested-by: Nathan Rossi <nathan@xxxxxxxxxxxxxxx>
>
> For reference this causes problems with DEBUG_RODATA (which changed to

Sorry typo -> s/causes/caused/, as in "... this [incorrect reserving
of the lower 512K] caused ...".

Regards,
Nathan

> default yes for CPU_V7 in v4.6) due to padding memory between
> .head.text and .text, allowing memory below 0x80000 to be available
> for allocation as non-reserved memory.
>
> Regards,
> Nathan
>
>>> ---
>>> Found when migrating from 4.1 to 4.6.
>>>
>>>  arch/arm/mach-zynq/common.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/mach-zynq/common.c b/arch/arm/mach-zynq/common.c
>>> index 6cefdb8..75885bc 100644
>>> --- a/arch/arm/mach-zynq/common.c
>>> +++ b/arch/arm/mach-zynq/common.c
>>> @@ -59,7 +59,7 @@ void __iomem *zynq_scu_base;
>>>  static void __init zynq_memory_init(void)
>>>  {
>>>         if (!__pa(PAGE_OFFSET))
>>> -               memblock_reserve(__pa(PAGE_OFFSET), __pa(swapper_pg_dir));
>>> +               memblock_reserve(__pa(PAGE_OFFSET), 0x80000);
>>>  }
>>>
>>>  static struct platform_device zynq_cpuidle_device = {
>>> --
>>> 2.9.3
>>>
>>>
>>> _______________________________________________
>>> linux-arm-kernel mailing list
>>> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>>
>>
>>
>> --
>> Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
>> w: www.monstr.eu p: +42-0-721842854
>> Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
>> Maintainer of Linux kernel - Xilinx Zynq ARM architecture
>> Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform