linux-kernel - Re: [PATCH] mm: bootmem: use phys_addr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <505123FE.2090305@ti.com>
Date:	Wed, 12 Sep 2012 20:08:30 -0400
From:	Cyril Chemparathy <cyril@...com>
To:	Tejun Heo <tj@...nel.org>
CC:	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	<akpm@...ux-foundation.org>, <davem@...emloft.net>,
	<eric.dumazet@...il.com>, <hannes@...xchg.org>,
	<shangw@...ux.vnet.ibm.com>, <vitalya@...com>
Subject: Re: [PATCH] mm: bootmem: use phys_addr_t for physical addresses

Hi Tejun,

On 9/12/2012 4:39 PM, Tejun Heo wrote:
> Hello,
>
> On Wed, Sep 12, 2012 at 12:06:48PM -0400, Cyril Chemparathy wrote:
>>   static void * __init alloc_bootmem_core(unsigned long size,
>>   					unsigned long align,
>> -					unsigned long goal,
>> -					unsigned long limit)
>> +					phys_addr_t goal,
>> +					phys_addr_t limit)
>
> So, a function which takes phys_addr_t for goal and limit but returns
> void * doesn't make much sense unless the function creates directly
> addressable mapping somewhere.
>

On the 32-bit PAE platform in question, physical memory is located 
outside the 4GB range.  Therefore phys_to_virt takes a 64-bit physical 
address and returns a 32-bit kernel mapped lowmem pointer.

> The right thing to do would be converting to nobootmem (ie. memblock)
> and use the memblock interface.  Have no idea at all whether that
> would be a realistic short-term solution for arm.
>

I must plead ignorance and let wiser souls chime in on ARM architecture 
plans w.r.t. nobootmem.  As far as I can tell, the only thing that 
blocks us from using nobootmem at present is the need for sparsemem on 
some platforms.

-- 
Thanks
- Cyril
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/