Re: Memory Concepts [+Newbie]

[Pei Lin <telent997@gmail.com>]

That book << Understating the Linux Virtual Memory Manager>> clearly
elaborate why ZONE_NORMAL is 896 on the section 4.1 Linear Address
Space.

SEE  the comment about ZONE_HIGHMEM,  include/linux/mmzone.h

#ifdef CONFIG_HIGHMEM
        /*
         * A memory area that is only addressable by the kernel through
         * mapping portions into its own address space. This is for example
         * used by i386 to allow the kernel to address the memory beyond
         * 900MB. The kernel will set up special mappings (page
         * table entries on i386) for each page that the kernel needs to
         * access.
         */
        ZONE_HIGHMEM,
#endif


2009/5/4 Mark Brown <markb@marksmachinations.com>:
> Hi Marcos,
>
> A memory bank for RAM is just an individual addressable array on a memory
> board. The addressing of the bank is managed by the memory controller.
>
> Regards,
> -- Mark
>
> On May 4, 2009, at 7:44 AM, Marcos Roriz wrote:
>
>> I'm reading Mel Gorman Understating the Linux Virtual Memory Manager and
>> also TANENBAUM Modern Operating System I don't get some basic concepts of
>> the Memory Management in Linux Kernel.
>>
>> The first question is, what is a memory bank, It's not clear if its a
>> physical section of the memory of if its a chip (physical) itself.
>>
>> The ZONE_NORMAL zone refer only to kernel direct memory mapped, that means
>> only to kernel pages and kernel programs (such as daemons)?
>>
>> Why is the ZONE_NORMAL so large (896 MB)? How to deal with low memory
>> systems?
>>
>> The ZONE_HIGHMEM zone refer to kernel not mapped directly, so that
>> includes userspace programs right?
>>
>> I googled and searched for all those answers but couldn't find a direct
>> and consistent answer, thats why I'm asking for your guys help.
>>
>> Thanks very much for you time,
>>
>> Marcos Roriz
>>
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>
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