AARCH64 text start address: why so low?

[Matt Thomas]

On Jan 20, 2014, at 7:51 PM, Andrew Pinski <pinskia@gmail.com> wrote:

> On Mon, Jan 20, 2014 at 7:50 PM, Andrew Pinski <pinskia@gmail.com> wrote:
>> On Mon, Jan 20, 2014 at 7:46 PM, Matt Thomas <matt@3am-software.com> wrote:
>>> 
>>> As I was looking at the aarch64 text start address for Linux, I
>>> wondered why it defaulted to 4MB (well within the first 4GB) instead
>>> of (like alpha, mips64 elf, sparc64, hppa64, etc.) defaulting to a
>>> starting address at or above 4GB.
>> 
>> Because that is the default one for all elf files.   x86_64 is the
>> same as aarch64 here.
>> 
>>> 
>>> Given there is a minimum of 39 address bits (512GB) of address space,
>>> skipping first 4 GB shouldn't be a problem.
>> 
>> I think it matters due to how the different code models work.  The
>> default code model is small which means fit in the lower 4 GB.  This
>> is just like x86_64's code models.
> 
> 
> And just like MIPS64 msym32 code model which we had this same
> discussion as we are having now for changing MIPS64 default load
> address too.

I primarily thought -msym32 was for kernels, not userland.  I did wonder
about a -msym32 equivalent for aarch64.