Re: [PATCH] x86_64: early memtest to find bad ram

[Ingo Molnar <mingo@elte.hu>]

* Yinghai Lu <yhlu.kernel.send@gmail.com> wrote:

> do simple memtest after init_memory_mapping
> 
> use find_e820_area_size to find all ram range that is not reserved.
> 
> and do some simple bits test to find some bad ram.
> 
> if find some bad ram, use reserve_early to exclude that range.

very nice patch! I always thought that this was the proper way to do 
memtest - and we could in fact also do something like this after SMP 
bringup, and hit the memory bus via multiple CPUs. [that will need a 
different enumeration though than e820 maps]

one structural observation: please make this unified functionality, so 
that 32-bit kernels can make use of it too.

a small style nit from scripts/checkpatch.pl:

> +//		printk(KERN_DEBUG "find_e820_area_size : e820 %d [%llx, %lx]\n", i, ei->addr, ei_last);

remove such lines or make them pr_debug(). (checkpatch also found more 
such cases)

also, please add a CONFIG_BOOTPARAM_MEMTEST=y option so that 
distributions can enable this by default in their debug kernels.

i've applied your current version to get some testing, please send delta 
patches against x86/latest.

	Ingo