-L DIR, --libdir DIR directories to search libraries in
-s, --hash16 Use 16-bit (BSD2) hashes instead of 32-bit djb2 hashes. Implies -fuse-dnload-loader. Only usable for 32-bit output.
-c, --crc32c Use Intel's crc32 intrinsic for hashing. Implies -fuse-dnload-loader. Conflicts with `--hash16'.
-n, --nx Use NX (i.e. don't use RWE pages). Costs the size of one phdr, plus some extra bytes on i386.
-s, --hash16 Use 16-bit (BSD2) hashes instead of 32-bit djb2 hashes. Implies -fuse-dnload-loader. Only
usable for 32-bit output.
-c, --crc32c Use Intel's crc32 intrinsic for hashing. Implies -fuse-dnload-loader. Conflicts with
`--hash16'.
-n, --nx Use NX (i.e. don't use RWE pages). Costs the size of one phdr, plus some extra bytes on
i386.
-d, --det Make the order of imports deterministic (default: just use whatever binutils throws at us)
-fno-use-interp Don't include a program interpreter header (PT_INTERP). If not enabled, ld.so has to be invoked manually by the end user.
-fno-align-stack Don't align the stack before running user code (_start). If not enabled, this has to be done manually. Frees 1 byte.
-fuse-nx Don't use one big RWE segment, but use separate RW and RE ones. Use this to keep strict kernels (PaX/grsec) happy. Costs at least the size of one program header entry.
-fuse-dnload-loader Use a dnload-style loader for resolving symbols, which doesn't depend on nonstandard/undocumented ELF and ld.so features, but is slightly larger. If not enabled, a smaller custom loader is used which assumes
glibc.
-fno-skip-zero-value Don't skip an ELF symbol with a zero address (a weak symbol) when parsing libraries at runtime. Try enabling this if you're experiencing sudden breakage. However, many libraries don't use weak symbols, so this
doesn't often pose a problem. Frees ~5 bytes.
-fuse-dt-debug Use the DT_DEBUG Dyn header to access the link_map, which doesn't depend on nonstandard/undocumented ELF and ld.so features. If not enabled, the link_map is accessed using data leaked to the entrypoint by ld.so,
which assumes glibc. Costs ~10 bytes.
-fuse-dl-fini Pass _dl_fini to the user entrypoint, which should be done to properly comply with all standards, but is very often not needed at all. Costs 2 bytes.
-fskip-entries Skip the first two entries in the link map (resp. ld.so and the vDSO). Speeds up symbol resolving, but costs ~5 bytes.
-fno-start-arg Don't pass a pointer to argc/argv/envp to the entrypoint using the standard calling convention. This means you need to read these yourself in assembly if you want to use them! (envp is a preprequisite for X11,
because it needs $DISPLAY.) Frees 3 bytes.
-funsafe-dynamic Don't end the ELF Dyn table with a DT_NULL entry. This might cause ld.so to interpret the entire binary as the Dyn table, so only enable this if you're sure this won't break things!
-fno-ifunc-support Support linking to IFUNCs. Probably needed on x86_64, but costs ~16 bytes. Ignored on platforms without IFUNC support.
-fifunc-strict-cconv On i386, if -fifunc-support is specified, strictly follow the calling convention rules. Probably not needed, but you never know.
-g, --debug Pass `-g' to the C compiler, assembler and linker. Only useful when `--debugout' is
specified.
-fuse-interp [Default ON] Include a program interpreter header (PT_INTERP). If not enabled, ld.so has to
be invoked manually by the end user. Disable with `-fno-use-interp'.
-falign-stack [Default ON] Align the stack before running user code (_start). If not enabled, this has to
be done manually. Costs 1 byte. Disable with `-fno-align-stack'.
-fskip-zero-value [Default: ON if `-fuse-dnload-loader' supplied, OFF otherwise] Skip an ELF symbol with a
zero address (a weak symbol) when parsing libraries at runtime. Try enabling this if you're
experiencing sudden breakage. However, many libraries don't use weak symbols, so this
doesn't often pose a problem. Costs ~5 bytes.Disable with `-fno-skip-zero-value'.
-fifunc-support [Default ON] Support linking to IFUNCs. Probably needed on x86_64, but costs ~16 bytes.
Ignored on platforms without IFUNC support. Disable with `-fno-fifunc-support'.
-fuse-dnload-loader Use a dnload-style loader for resolving symbols, which doesn't depend on
nonstandard/undocumented ELF and ld.so features, but is slightly larger. If not enabled, a
smaller custom loader is used which assumes glibc. `-fskip-zero-value' defaults to ON if
this flag is supplied.
-fuse-nx Don't use one big RWE segment, but use separate RW and RE ones. Use this to keep strict
kernels (PaX/grsec) happy. Costs at least the size of one program header entry.
-fuse-dt-debug Use the DT_DEBUG Dyn header to access the link_map, which doesn't depend on
nonstandard/undocumented ELF and ld.so features. If not enabled, the link_map is accessed
using data leaked to the entrypoint by ld.so, which assumes glibc. Costs ~10 bytes.
-fuse-dl-fini Pass _dl_fini to the user entrypoint, which should be done to properly comply with all
standards, but is very often not needed at all. Costs 2 bytes.
-fskip-entries Skip the first two entries in the link map (resp. ld.so and the vDSO). Speeds up symbol
resolving, but costs ~5 bytes.
-fno-start-arg Don't pass a pointer to argc/argv/envp to the entrypoint using the standard calling
convention. This means you need to read these yourself in assembly if you want to use them!
(envp is a preprequisite for X11, because it needs $DISPLAY.) Frees 3 bytes.
-funsafe-dynamic Don't end the ELF Dyn table with a DT_NULL entry. This might cause ld.so to interpret the
entire binary as the Dyn table, so only enable this if you're sure this won't break things!
-fifunc-strict-cconv On i386, if -fifunc-support is specified, strictly follow the calling convention rules.
Probably not needed, but you never know.
--nasm NASM which nasm binary to use
--cc CC which cc binary to use (MUST BE GCC!)
--readelf READELF which readelf binary to use
@ -70,10 +96,13 @@ optional arguments:
Flags to pass to the linker for the final linking step
--smolrt SMOLRT Directory containing the smol runtime sources
--smolld SMOLLD Directory containing the smol linker scripts
--gen-rt-only Only generate the headers/runtime assembly source file, instead of doing a full link. (I.e. fall back to pre-release behavior.)
--gen-rt-only Only generate the headers/runtime assembly source file, instead of doing a full link. (I.e.
fall back to pre-release behavior.)
--verbose Be verbose about what happens and which subcommands are invoked
--keeptmp Keep temp files (only useful for debugging)
--debugout DEBUGOUT Write out an additional, unrunnable debug ELF file with symbol information. (Useful for debugging with gdb, cannot be ran due to broken relocations.)
--debugout DEBUGOUT Write out an additional, unrunnable debug ELF file with symbol information. (Useful for
debugging with gdb, cannot be ran due to broken relocations.)
--hang-on-startup Hang on startup until a debugger breaks the code out of the loop. Only useful for debugging.
```
A minimal crt (and `_start` funcion) are provided in case you want to use `main`.
@ -86,7 +115,7 @@ during dynamic linking. (Think of it as an equivalent of `ldd`, except that it
also checks whether the imported functions are present as well.)
PoroCYon
11 months ago