Virtual Address Space

[piyush moghe]

Please refer to following links, I hope this will help in
understanding of linker generated address and virtual process address
space:

http://www.linuxjournal.com/article/6463?page=0,0
http://www.tenouk.com/ModuleW.html

Regards.
Piyush

On Fri, Sep 30, 2016 at 10:39 PM,  <roman at mailoo.org> wrote:
> Hi,
>
> I compile main.s and it generates main.o. With objdump I can see:
>
> 0000000000000000 <_start>:
>    0: b8 01 00 00 00        mov    $0x1,%eax
>    5: bb 00 00 00 00        mov    $0x0,%ebx
>    a: cd 80                         int    $0x80
>
> After link main.o it generates main. With objdump I now can see:
>
> 0000000000400078 <_start>:
>   400078: b8 01 00 00 00        mov    $0x1,%eax
>   40007d: bb 00 00 00 00        mov    $0x0,%ebx
>   400082: cd 80                         int    $0x80
>
> So, linker generates virtual address, doesn't it? But why it starts at
> 400078 and not in other any location? Is there any logic here? A virtual
> address can start at 0?
>
> Regards.
>
> El 29.09.2016 09:25, arshad hussain escribió:
>
>
> On 28-Sep-2016, at 10:36 am, Madhu K <madhu.sk89 at gmail.com> wrote:
>
> Hi All,
>
>
> The support comes right through from the architecture.
>
> Linear address: Also virtual address. This is Address CPU can address. This
> is 0 - 4GB under 32bit architecture.
> Physical address: This are actual memory installed in your system. Linear
> address have to be converted to
> physical address eventually. MMU translate linear address with the help of
> paging to physical address.
>
>
>
> This is to understand the Virtual address space.Basically who generates the
> virtual addresses CPU or GNU compiler?
>
>
> A program image generated by compiler & linker uses Virtual Address . During
> execution of the program CPU + MMU
> translates or maps each virtual address to physical address.
>
> Net-net this is architecture dependent and would highly recommend reading
> Intel's Architecture Manual for your reference.
>
>
> Thanks
> Madhu
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