Re: Difference between *-none-elf and *-linux-gnu configurations

[Johannes Krottmayer <johannes@krotti42.com>]

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Hi Jonathan!

Thanks for the answer.

On 4/12/24 17:14, Jonathan Wakely via Gcc-help wrote:
> On Fri, 12 Apr 2024, 15:26 Johannes Krottmayer via Gcc-help, <
> gcc-help@gcc.gnu.org> wrote:
>
>> Hi!
>>
>> Sorry if already asked, but what are the differences from as example
>> x86_64-none-elf and x86_64-linux-gnu configurations?
>>
> The former is a bare metal "freestanding" target that generates code for a
> system without an OS or C library. The latter is a "hosted" target that
> uses the Linux kernel and Glibc C library.
>
I already did know that. The *-none-elf configurations I primarily use them
in my own embedded projects. But there seems for me, there are more 
differences.

>> I have tried to compile Linux with a x86_64-none-elf build, but failed with
>> assembler errors. (It's might be also a binutils question.) With the
>> x86_64-linux-gnu build, everything worked fine.
>>
>
> You need a binutils configured for x86_64-none-elf to assemble and link
> co
de compiled for that target.
Yes, the binutils are configured as *-none-elf. For my projects these
configuration works fine. But I'm wondering why the x86_64-none-elf build
didn't work when I try to compile the Linux kernel. AFAIK, Linux use it's
own libc and also some functions from libgcc.

So I have thought there must be another differences. Like how comments
are interpreted, as example (The assembler error, when I try to build
Linux with a x86_64-none-elf is inner a comment.).

Currently I have only compared the Makefile from GCC after configuration,
and only seen that additional _GNU_SOURCE is defined in the *-linux-gnu
configuration.
>
>> Can somebody explain me the key differences between this both builds?
>> Unfortunately I currently didn't find any information.
>>
>> Thanks in advance!
>>
>> Kind regards,
>>
>> Johannes
>>


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