| aout.4 (b80225cd7b7012df7fff1cd4809ecec6d256a667) | aout.4 (ecb84463033bcaadd90c1860e7aa90a0613a3cf7) |
|---|---|
| 1.\" Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org> 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright --- 21 unchanged lines hidden (view full) --- 30.Nd kernel support for executing binary files in legacy a.out format 31.Sh SYNOPSIS 32.Bd -literal -offset indent 33kldload a.out 34.Ed 35.Sh DESCRIPTION 36The 37.Xr a.out 5 | 1.\" Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org> 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright --- 21 unchanged lines hidden (view full) --- 30.Nd kernel support for executing binary files in legacy a.out format 31.Sh SYNOPSIS 32.Bd -literal -offset indent 33kldload a.out 34.Ed 35.Sh DESCRIPTION 36The 37.Xr a.out 5 |
| 38executable format was used by 39.Fx 40of versions \*(Lt 3.0. 41Since only i386 architecture was supported at that time, the | 38executable format was used before the release of 39.Fx 3.0. 40Since i386 was the only supported architecture at that time, |
| 42.Xr a.out 5 | 41.Xr a.out 5 |
| 43executables can only be activated on the platforms that support 44execution of i386 code, which are i386, amd64 and (partially) ia64. | 42executables can only be activated on platforms that support 43execution of i386 code, such as i386, amd64 and (partially) ia64. |
| 45.Pp 46To add kernel support for old syscalls and old syscall invocation methods, | 44.Pp 45To add kernel support for old syscalls and old syscall invocation methods, |
| 47you need to place the following options in the kernel configuration file: | 46place the following options in the kernel configuration file: |
| 48.Bd -ragged -offset indent 49.Cd "options COMPAT_43" 50.br 51.Cd "options COMPAT_FREEBSD32" 52.Ed 53.Pp 54The 55.Va COMPAT_FREEBSD32 56option is only required on 64-bit CPU architectures. 57.Pp 58The 59.Va aout.ko | 47.Bd -ragged -offset indent 48.Cd "options COMPAT_43" 49.br 50.Cd "options COMPAT_FREEBSD32" 51.Ed 52.Pp 53The 54.Va COMPAT_FREEBSD32 55option is only required on 64-bit CPU architectures. 56.Pp 57The 58.Va aout.ko |
| 60module must be loaded to get support for | 59module needs to be loaded with the 60.Xr kldload 8 61utility in order to support the |
| 61.Xr a.out 5 | 62.Xr a.out 5 |
| 62image activator. 63Use the command | 63image activator: |
| 64.Bd -ragged -offset indent 65.Ic kldload aout 66.Ed | 64.Bd -ragged -offset indent 65.Ic kldload aout 66.Ed |
| 67or put the following line in | 67.Pp 68Alternatively, to load the module at boot time, place the following line in |
| 68.Xr loader.conf 5 : 69.Bd -literal -offset indent 70aout_load="YES" 71.Ed 72.Pp 73The 74.Xr a.out 5 | 69.Xr loader.conf 5 : 70.Bd -literal -offset indent 71aout_load="YES" 72.Ed 73.Pp 74The 75.Xr a.out 5 |
| 75format was mainstream quite long time ago. 76The reasonable default settings and security requirements of the 77modern OS contradict to the default environment of that time and | 76format was mainstream quite a long time ago. 77Reasonable default settings and security requirements of 78modern operating systems today contradict the default environment of that time and |
| 78require adjustments of the system to mimic natural environment for 79old binaries. 80.Pp 81The following 82.Xr sysctl 8 83tunables are useful for this: 84.Bl -tag -offset indent -width "XXXXXXXXXXXXXXXXXXXXXXXXX" 85.It Xo Va security.bsd.map_at_zero 86.Xc | 79require adjustments of the system to mimic natural environment for 80old binaries. 81.Pp 82The following 83.Xr sysctl 8 84tunables are useful for this: 85.Bl -tag -offset indent -width "XXXXXXXXXXXXXXXXXXXXXXXXX" 86.It Xo Va security.bsd.map_at_zero 87.Xc |
| 87Set to 1 to allow the mapping of process pages at the address 0. | 88Set to 1 to allow mapping of process pages at address 0. |
| 88Some very old 89.Va ZMAGIC | 89Some very old 90.Va ZMAGIC |
| 90executable images require the text mapping at the address 0. | 91executable images require text mapping at address 0. |
| 91.It Xo Va kern.pid_max 92.Xc 93Old versions of 94.Fx 95used 16-bit types for 96.Vt pid_t . 97Current kernels use 32-bit type for 98.Vt pid_t , | 92.It Xo Va kern.pid_max 93.Xc 94Old versions of 95.Fx 96used 16-bit types for 97.Vt pid_t . 98Current kernels use 32-bit type for 99.Vt pid_t , |
| 99and allow the process id's up to 99999. | 100and allow process id's up to 99999. |
| 100Such values cannot be represented by old 101.Vt pid_t , | 101Such values cannot be represented by old 102.Vt pid_t , |
| 102mostly causing issues for the processes using | 103mostly causing issues for processes using |
| 103.Xr wait 2 | 104.Xr wait 2 |
| 104syscalls, for instance, shells. | 105syscalls, for example shells. |
| 105Set the sysctl to 30000 to work around the problem. 106.It Xo Va kern.elf32.read_exec 107.Xc 108Set to 1 to force any accessible memory mapping performed by 32-bit 109process to allow execution, see 110.Xr mmap 2 . 111Old i386 CPUs did not have a bit in PTE which disallowed execution | 106Set the sysctl to 30000 to work around the problem. 107.It Xo Va kern.elf32.read_exec 108.Xc 109Set to 1 to force any accessible memory mapping performed by 32-bit 110process to allow execution, see 111.Xr mmap 2 . 112Old i386 CPUs did not have a bit in PTE which disallowed execution |
| 112from the page, so many old programs did not specified | 113from the page, so many old programs did not specify |
| 113.Va PROT_EXEC 114even for mapping of executable code. 115The sysctl forces 116.Va PROT_EXEC 117if mapping has any access allowed at all. 118The setting is only needed if the host architecture allows 119non-executable mappings. 120.El 121.Sh SEE ALSO 122.Xr execve 2 , 123.Xr a.out 5 , 124.Xr elf 5 , 125.Xr sysctl 8 . | 114.Va PROT_EXEC 115even for mapping of executable code. 116The sysctl forces 117.Va PROT_EXEC 118if mapping has any access allowed at all. 119The setting is only needed if the host architecture allows 120non-executable mappings. 121.El 122.Sh SEE ALSO 123.Xr execve 2 , 124.Xr a.out 5 , 125.Xr elf 5 , 126.Xr sysctl 8 . |
| 126.Sh BUGS 127On 64bit architectures, not all wrappers for older syscalls are implemented. | |
| 128.Sh HISTORY 129The 130.Xr a.out 5 131executable format was used on ancient 132.At 133and served as the main executable format for 134.Fx | 127.Sh HISTORY 128The 129.Xr a.out 5 130executable format was used on ancient 131.At 132and served as the main executable format for 133.Fx |
| 135from inception up to | 134from the beginning up to |
| 136.Fx 2.2.9 . 137In 138.Fx 3.0 139it was superseded by 140.Xr elf 5 . 141.Sh AUTHORS 142The 143.Nm 144manual page was written by 145.An Konstantin Belousov Aq kib@FreeBSD.org . | 135.Fx 2.2.9 . 136In 137.Fx 3.0 138it was superseded by 139.Xr elf 5 . 140.Sh AUTHORS 141The 142.Nm 143manual page was written by 144.An Konstantin Belousov Aq kib@FreeBSD.org . |
| 145.Sh BUGS 146On 64bit architectures, not all wrappers for older syscalls are implemented. |
|