linux-kernel - Re: [PATCH] [powerpc] Export memory limit via device tree

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Message-ID: <5007BEB2.5060405@in.ibm.com>
Date:	Thu, 19 Jul 2012 13:30:50 +0530
From:	"Suzuki K. Poulose" <suzuki@...ibm.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	mahesh@...ux.vnet.ibm.com, hbabu@...ibm.com
Subject: Re: [PATCH] [powerpc] Export memory limit via device tree

On 07/11/2012 11:06 AM, Benjamin Herrenschmidt wrote:
>> diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
>> index c957b12..0c9695d 100644
>> --- a/arch/powerpc/kernel/machine_kexec.c
>> +++ b/arch/powerpc/kernel/machine_kexec.c
>> @@ -207,6 +207,12 @@ static struct property crashk_size_prop = {
>>   	.value = &crashk_size,
>>   };
>>
>> +static struct property memory_limit_prop = {
>> +	.name = "linux,memory-limit",
>> +	.length = sizeof(phys_addr_t),
>> +	.value = &memory_limit,
>> +};
>> +
>
> AFAIK. phys_addr_t can change size, so instead make it point to a known
> fixes size quantity (a u64).
Ben,

Sorry for the delay in the response.

Some of the other properties are also of phys_addr_t, (e.g 
linux,crashkernel-base, linux,kernel-end ). Should we fix them as well ?

Or

Should we leave this also a phys_addr_t and let the userspace handle it ?

>
>> +
>> +	/* memory-limit is needed for constructing the crash regions */
>> +	prop = of_find_property(node, memory_limit_prop.name, NULL);
>> +	if (prop)
>> +		prom_remove_property(node, prop);
>> +
>> +	if (memory_limit)
>> +		prom_add_property(node, &memory_limit_prop);
>> +
>
> There's a patch floating around making prom_update_property properly
> handle both pre-existing and non-pre-existing props, you should probably
> base yourself on top of it. I'm about to stick that patch in powerpc
> -next
>
OK. I am testing the new patch based on the above commit. I will wait
for the clarification on the issue of the type, before I post it here.

Thanks
Suzuki

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