QemuUserModeToDo [FreeBSD WIKI]

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===== Qemu User Mode for FreeBSD ToDo List =====

While Qemu user mode is fairly well supported on Linux it lacks a lot of code to support this feature on %%FreeBSD%%.

This page tracks the latest work being done to add the missing code to add support for some of the more popular CPU architectures.

===== Contact =====

If you are interested in helping please contact SeanBruno or StaceySon.

Code is available in the [[https://github.com/seanbruno/qemu-bsd-user|GitHub: seanbruno/qemu-bsd-user repository]].

===== Missing Features/Known Bugs and Status =====

^ Feature/Bug ^ Description ^ Notes ^ Status/Who ^
| ARM arch | Missing some ARM dependent bits. | sigframe and sigreturn trampoline,  thread startup in new_thread_start(),  maybe some sysarch() stuff, set_mcontext/get_mcontext, etc. | Done. sson |
| MIPS arch | mips64 is done. Missing some mips32 dependent bits. |  | Done. sbruno |
| SPARC64 arch | Missing SPARC64 dependent bits. | demand? Definitely! |  |
| PPC/PPC64 arch | Missing PPC/PPC64 dependent bits. | Work started, almost runs static binaries (ppc32) | JustinHibbits |
| thread cancel | SIGTHR is used by underlining thread code in QEMU | May use a different sig number for the emulated SIGTHR | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/c62b5a09ad06c813e46f61ee8fb68260becb9dfc|Done.]] |
| sysctl()/getrlimit() | Sysctl's KERN_USRSTACK, KERN_PS_STRINGS, and getrlimit(RLIMIT_STACK..) need to return emulator addresses and stack size | Increasing stack size with setrlimit() is problematic so it is not supported. | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/28b28e1b4615526b32478eb02f07f9c2acad550f|Done]] |
| Special sysctl(mib[0]=0, mib[1]=3) | The return returned data for the special sysctl() to convert a name (e.g. "kern.smu.cpus") to its mib/oid is not properly byte swapped for mixed endian host/target. | Handle the special case for swapping. | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/a344a133b4fb03bc5251f3098a5ab827e16898a2|Done.]] |
| Missing sockopt options | see bsd-user/syscall.c do_getsockopt()/do_setsockopt() |  |  |
| ioctl commands | More ioctl commands need to be added.  See bsd-user/freebsd/ioctls.h | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/64a21e9826db83792607592d5706c76cd828b6e3|Added sys/filio.h ioctl's.]] |  |
| _umtx_op() | This code needs to be reviewed and maybe improved. | UMTX_OP_MUTEX_WAIT doesn't seem correct. |  |
| Code cleanup | %%FreeBSD%% dependent code needs to go in bsd-user/%%FreeBSD%%.  ARCH dependent code needs to go into bsd-user/arm, etc. | bsd-user/syscall.c and bsd-user/syscall_defs.h need lots of love. | [[https://github.com/staceyson/qemu-bsd-user/tree/bsd-user-mips64|Done.]]  [[http://people.freebsd.org/~sson/qemu/qemu-mips64/|Patches]] |
| %%NetBSD%%/%%OpenBSD%% | Broken by %%FreeBSD%% port.  Need to be fixed as part of code cleanup. |  | Done (see above). Needs testing. |
| Dynamically linked executables | Currently I have only been testing with statically linked executables. | The code is mostly there for dynamically linked executables. | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/8bd8522f11382f09722845245eebd9580e5541e4|Done]] |
| execve() hack | In the execve() syscall shim check the target executable's ELF header for e_machine=EM_MIPS, e_ident=ELFCLASS64%%|%%ELFOSABI_FREEBSD, etc. and automatically insert "qemu-mips64" as the path and the path in front of the argv list. | fexecve() is a problem. Passing the FD to new qemu-mips64 instance might be a good work-around. | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/4d70225e5063bc63d4abad154390e37eab84d1f6|Done]] |
| sysctl() for mmap_min_addr | The guest_base command-line option tried to open "/proc/sys/vm/mmap_min_addr" to determine the minimum virtual address (main.c).  This needs to be replaced with the proper sysctl. |  |  |
| "sysconf pages: Cannot allocate memory" | During "Finding dependencies in ports build we get "sysconf pages: Cannot allocate memory".  Most likely a sysctl() problem. | sysconf(_SC_PHYS_PAGES) is failing on arm arch. This is a 32-bit target on a 64-bit host issue. Workaround: Run on 32-bit host. |  |
| sysctl() returning struct | Some sysctl() oid's return structs such as KERN_CLOCKRATE, KERN_VNODE, KERN_PROC, KERN_FILE, KERN_BOOTTIME, etc. | Maybe do something like ioctl() with sysctl() using thunk. |  |
| interrupted read() | SIGINT during a blocked read() results in a core dump. |  | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/abf07d643e1f4f3cb0de7a761b82751fb57decbf|Done.]] |
| Perl 5.14 regression test failures | UPDATE: "Failed 2 tests out of 1970, 99.90% okay."  cpan/%%ExtUtils%%-MakeMaker/t/fixin fails test 'switch retained'at t/fixin.t line 77. op/magic fails show-shebang: print: not found at line 253. | Bug fixes: [[https://github.com/staceyson/qemu-devel-1.4.0/commit/5a3b8a0f1e2cbf04fde4e0965e012d24d9aa0f29|5a3b8a0f1e]], [[https://github.com/staceyson/qemu-devel-1.4.0/commit/71c890d48caedba350b888a151cb6ae8d2e4f91a|71c890d48c]], [[https://github.com/staceyson/qemu-devel-1.4.0/commit/94db009c1729a2744f6d76748bb8812f47b49a25|94db009c17]], [[https://github.com/staceyson/qemu-devel-1.4.0/commit/6a1eccb851588f4a1021d71eebcb084c5a44c290|6a1eccb851]], [[https://github.com/staceyson/qemu-devel-1.4.0/commit/f85dca9064abf94168afa554ad4ab51236798607|f85dca9064]] | sson@ |
| 'uname -m' and 'uname -p' | uname(1) will return the host arch instead of the target arch.  Some port configure scripts will use this information. | It gets it from sysctl: hw.machine & hw.machine_arch | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/5b26fc7276662d29506dfbe020c1c73892325cd3|done.]] |
| Performance:  init_paths() | For dynamically linked target binaries, init_paths() walks a bunch of directory paths on start up.  It might be good to create a cache file or figure a better way or something. | done (backported from upstream) |  |
| Thr (parent) exit seg fault | Running the attached program results in "%%<%%jemalloc>: contrib/jemalloc/include/jemalloc/internal/arena.h:942: Failed assertion: "arena_mapbits_allocated_get(chunk, pageind) != 0" (in target code) and then seg fault in gen_intermediate_code() in qemu-mips64.  The tb doesn't seem valid.  Looks like thread is still running after main() has exited? | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/1879719cea4712c3ea233421fcaf2ddbabcf0795|bug fix for the case of the parent exiting before child thread.]] | done. |
| The (child) exit seg fault | When the child thread exits it seg faults in arena_chunk_dirty_insert() (jemalloc).  The call path of the child is as follows:  pthread_exit() -> _malloc_thread_cleanup() -> __jemalloc_tcache_tsd_cleanup_wrapper() -> ... -> arena_chunk_dirty_insert()__ | Thread stack pointer needs to be pointing at the top of the stack and not the bottom. | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/8dd4a92ea5e5c61104d68ec47466fb0e9a4ed0ba|Fixed.]] |
| Unsupported ioctl: cmd=0xffffffffc1206949 | SIOCGIFAFLAG_IN6        _IOWR('i', 73, struct in6_ifreq) |  |  |

==== Missing System Call Shims ====

^ Syscall(s) ^ Notes ^ Status/Who ^
| ktimer_*() | Needed? |  |
| __acl_*()/extattr_*()__ | extattr_'s and __acl's are needed by tar, etc.__ | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/b231eb105f39dc669284f7734549f9b2b105eb09|Done.]] |
| cpuset_*() |  |  |
| rctl_*() | Needed? |  |
| sctp_*() |  |  |
| kld*()/mod*() |  |  |
| quota*() |  |  |
| jail*() | Would be difficult to emulate. |  |
| cap_*() | Would be difficult to emulate. |  |
| _mac*() | Needed? |  |
| sendfile() |  |  |
| ptrace() | Would be difficult to emulate. |  |
| utrace() | Needed? |  |
| freebsd6_*() |  |  |
| setsockopt()/getsockopt() | Missing some options.  see bsd-user/syscall.c do_getsockopt()/do_setsockopt() |  |
| ioctl() | Only tty(4) currently supported.  Need more ioctl commands.  See bsd-user/freebsd/ioctl.h |  |
| rtprio_thread() |  | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/0fb559214a980cfe22850ea015ebb3163c68e644|Done]] |
| swapcontext() | setcontext()/getcontext() are done so this should be easy. |  |
| thr_create() | Not sure if it is used.  All the code I have seen uses thr_new() |  |
| fexecve() |  | [[https://github.com/staceyson/qemu-devel-1.4.0/commit/145271eb03b9e15fe908417a167c562efbbf8fd9|Done.]] |

[[QemuUserModeHowTo|FreeBSD Qemu User Mode HowTo]]

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{{tag>Virtualization}}
{{tag>Todo}}
{{tag>Stale}}