GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 2.1AS(Slurm) |
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iopl(2) |
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iopl − change I/O privilege level
#include
<unistd.h> /* for libc5 */
#include <sys/io.h> /* for glibc */
int iopl(int level);
iopl changes the I/O privilege level of the current process, as specified in level.
This call is necessary to allow 8514-compatible X servers to run under Linux. Since these X servers require access to all 65536 I/O ports, the ioperm call is not sufficient.
In addition to granting unrestricted I/O port access, running at a higher I/O privilege level also allows the process to disable interrupts. This will probably crash the system, and is not recommended.
Permissions are inherited by fork and exec.
The I/O privilege level for a normal process is 0.
On success, zero is returned. On error, −1 is returned, and errno is set appropriately.
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EINVAL |
level is greater than 3. |
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EPERM |
The current user is not the super-user. |
iopl has to be used when you want to access the I/O ports beyond the 0x3ff range: to get the full 65536 ports bitmapped you’d need 8kB of bitmaps/process, which is a bit excessive.
iopl is Linux specific and should not be used in processes intended to be portable.
Libc5 treats it as a system call and has a prototype in <unistd.h>. Glibc1 does not have a prototype. Glibc2 has a prototype both in <sys/io.h> and in <sys/perm.h>. Avoid the latter, it is available on i386 only.
ioperm(2)
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iopl(2) | |