Re: ELF e_ident[EI_OSABI] not being set on objects?

> On Jan 8, 2025, at 7:46 AM, Joseph Koshy <[email protected]> wrote:
> 
> I noticed that NetBSD/evbarm binaries are being built as 'SysV' binaries.
> 
> nbarm% readelf -h /usr/bin/nm | grep OS/ABI
>  OS/ABI:                            UNIX - System V
> nbarm% readelf -h /usr/lib/libc.so | grep OS/ABI
>  OS/ABI:                            UNIX - System V
> 
> This was on recent -current:
> 
> % uname -a
> NetBSD nbarm 10.99.12 NetBSD 10.99.12 (GENERIC64) #0: Fri Dec 27
> 00:57:53 UTC 2024
> [email protected]:/usr/src/sys/arch/evbarm/compile/GENERIC64
> evbarm
> 
> Any idea why the e_ident[EI_OSABI] field isn't being set to ELFOSABI_NETBSD?

I believe that is intentional. Running the same command on NetBSD/amd64
gives the same output.

Running "man 5 elf" shows

         EI_OSABI       Contains the operating system ABI identifica-
                                 tion. Note that even though the definition
                                 ELFOSABI_NETBSD exists, NetBSD uses
                                 ELFOSABI_SYSV here, since the NetBSD ABI does
                                 not deviate from the standard.

The ELF binary can contain an ELF PT_NOTE to show that it's meant for NetBSD. See

https://www.netbsd.org/docs/kernel/elf-notes.html

> Thanks,
> Joseph Koshy