lkml.org 
[lkml]   [2007]   [May]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH]: linux-2.6.21-uc0 (MMU-less updates)
Robin Getz wrote:
> On Thu 3 May 2007 07:03, Greg Ungerer pondered:
>> Robin Getz wrote:
>>> On Wed 2 May 2007 07:32, Greg Ungerer pondered:
>>>> Robin Getz wrote:
>>>>> I was trying to understand why we don't want to do the same checking on
>>>>> noMMU?
>>>> The problem is on systems that have RAM mapped at high physical
>>>> addresses. TASK_SIZE may well be a numerically smaller number
>>>> than the address range that RAM sits in. So this test fails when
>>>> it shouldn't.
>>> So, then this is a problem only on one or two architectures, not all
>>> noMMU platforms?
>> Its not an architecture problem. It can effect any board that
>> has RAM mapped at a large numerical addresses (larger than TASK_SIZE).
>> So it can effect any non-MMU platform.
>
> Depending on how TASK_SIZE is defined - it looks like everyone else forces it
> to end of memory, except 68k[nommu].
>
> asm-arm/memory.h:#define TASK_SIZE (CONFIG_DRAM_SIZE)
> asm-blackfin/processor.h:#define TASK_SIZE (memory_end)
> asm-frv/mem-layout.h:#define TASK_SIZE __UL(0xFFFFFFFFUL)
>
> asm-m68k/processor.h:#define TASK_SIZE (0xF0000000UL)
> asm-m68k/processor.h:#define TASK_SIZE (0x0E000000)
> asm-m68k/processor.h:#define TASK_SIZE (0x0E000000UL)
> asm-m68knommu/processor.h:#define TASK_SIZE (0xF0000000UL)

Probably too:

asm-sh/processor.h:#define TASK_SIZE 0x7c000000UL

which has some parts with MMU.

There have been others out of tree that have it like this to.


> I'm happy to learn we are doing something wrong, but I think that we just
> copied the arm/frv setup.

That is one way to handle it. Have you followed all the other
uses of TASK_SIZE and verified it is not a problem?

Regards
Greg



------------------------------------------------------------------------
Greg Ungerer -- Chief Software Dude EMAIL: gerg@snapgear.com
SnapGear -- a Secure Computing Company PHONE: +61 7 3435 2888
825 Stanley St, FAX: +61 7 3891 3630
Woolloongabba, QLD, 4102, Australia WEB: http://www.SnapGear.com
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-05-03 15:33    [W:0.141 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site