Linux file command: what does SYSV mean?

Question

I am digging two legacy cross-compiled assemblies of ARM Linux. There is not much documentation other than “use this virtual machine image to create a source”. The only difference between the output of the file command is the presence of "(SYSV)"

# file Executable Executable: ELF 32-bit LSB executable, ARM, version 1 (SYSV) ... 

What can I accept based on the presence or absence of SYSV in a string?

Answer 1

If you see the line (SYSV) , this means that the e_ident[EI_OSABI] field in the ELF header is 0. From the ELF specification (PDF link) :

 Table 5. Operating System and ABI Identifiers, e_ident[EI_OSABI] Name Value Meaning ELFOSABI_SYSV 0 System V ABI ELFOSABI_HPUX 1 HP-UX operating system ELFOSABI_STANDALONE 255 Standalone (embedded) application 

My local file /usr/share/file/magic/elf has a longer list:

 # Up to now only 0, 1 and 2 are defined; I've seen a file with 0x83, it seemed # like proper ELF, but extracting the string had bad results. >4 byte <0x80 >>8 string >\0 (%s) >8 string \0 >>7 byte 0 (SYSV) >>7 byte 1 (HP-UX) >>7 byte 2 (NetBSD) >>7 byte 3 (GNU/Linux) >>7 byte 4 (GNU/Hurd) >>7 byte 5 (86Open) >>7 byte 6 (Solaris) >>7 byte 7 (Monterey) >>7 byte 8 (IRIX) >>7 byte 9 (FreeBSD) >>7 byte 10 (Tru64) >>7 byte 11 (Novell Modesto) >>7 byte 12 (OpenBSD) >8 string \2 >>7 byte 13 (OpenVMS) >>7 byte 97 (ARM) >>7 byte 255 (embedded) 

Here is the ELF header and offsets for your reference (from this link ):

 #define EI_NIDENT 16 typedef struct { unsigned char e_ident[EI_NIDENT]; Elf32_Half e_type; Elf32_Half e_machine; Elf32_Word e_version; Elf32_Addr e_entry; Elf32_Off e_phoff; Elf32_Off e_shoff; Elf32_Word e_flags; Elf32_Half e_ehsize; Elf32_Half e_phentsize; Elf32_Half e_phnum; Elf32_Half e_shentsize; Elf32_Half e_shnum; Elf32_Half e_shstrndx; } Elf32_Ehdr; Figure 4-4: e_ident[] Identification Indexes Name Value Purpose EI_MAG0 0 File identification EI_MAG1 1 File identification EI_MAG2 2 File identification EI_MAG3 3 File identification EI_CLASS 4 File class EI_DATA 5 Data encoding EI_VERSION 6 File version EI_OSABI 7 Operating system/ABI identification EI_ABIVERSION 8 ABI version EI_PAD 9 Start of padding bytes EI_NIDENT 16 Size of e_ident[]