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 <[email protected]> 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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