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← Revision 9 as of 2021-01-12 06:38:58 ⇥
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| http://kerneltrap.org/man/linux/man4/kmem.4 | * see `man 4 kmem` |
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| . memfP is a character device file that is an image of the main memory of the computer. It may be used, for example, to examine (and even patch) the system. Byte addresses in mem are interpreted as physical memory addresses. References to non-existent locations cause errors to be returned. Examining and patching is likely to lead to unexpected results when read-only or write-only bits are present. It is typically created by: mknod -m 660 /dev/mem c 1 1 chown root:kmem /dev/mem The file kmem is the same as mem , except that the kernel virtual memory rather than physical memory is accessed. It is typically created by: mknod -m 640 /dev/kmem c 1 2 chown root:kmem /dev/kmem portfP is similar to mem , but the I/O ports are accessed. It is typically created by: mknod -m 660 /dev/port c 1 4 chown root:mem /dev/port And here is the description on the difference between kmem and mem. |
/dev/mem is typically created by: * mknod -m 660 /dev/mem c 1 1 * chown root:kmem /dev/mem The file kmem is the same as mem, except that the kernel virtual memory rather than physical memory is accessed. /dev/kmem is typically created by: * mknod -m 640 /dev/kmem c 1 2 * chown root:kmem /dev/kmem /dev/port is similar to mem, but the I/O ports are accessed. It is typically created by: * mknod -m 660 /dev/port c 1 4 * chown root:mem /dev/port Here is the description on the difference between kmem and mem. |
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[PATCH] Fix mmap_kmem (was: [question] What's the difference between /dev/kmem and /dev/mem) [Posted August 16, 2005 by corbet] From: Steven Rostedt <rostedt-AT-goodmis.org> To: LKML <linux-kernel-AT-vger.kernel.org> Subject: [PATCH] Fix mmap_kmem (was: [question] What's the difference between /dev/kmem and /dev/mem) Date: Thu, 11 Aug 2005 21:15:02 -0400 Cc: Andrew Morton <akpm-AT-osdl.org>, Linus Torvalds <torvalds-AT-osdl.org> ~+http://lwn.net/Articles/147902/ +~ ~+[Posted August 16, 2005 by corbet] +~ ~+ +~ ~+ +~~+ +~~+ +~~+ +~~+ +~ ||<^>~+'''From''':+~||~+ +~||<^>~+Steven Rostedt <rostedt-AT-goodmis.org>+~|| ||<^>~+'''To''':+~||~+ +~||<^>~+LKML <linux-kernel-AT-vger.kernel.org>+~|| ||<^>~+'''Subject''':+~||~+ +~||<^>~+[PATCH] Fix mmap_kmem (was: [question] What's the difference between /dev/'''kmem''' and /dev/mem)+~|| ||<^>~+'''Date''':+~||~+ +~||<^>~+Thu, 11 Aug 2005 21:15:02 -0400+~|| ||<^>~+'''Cc''':+~||~+ +~||<^>~+Andrew Morton <akpm-AT-osdl.org>, Linus Torvalds <torvalds-AT-osdl.org>+~|| {{{ }}} |
Here is how the kmem can be statically created:
see man 4 kmem
/dev/mem is typically created by:
- mknod -m 660 /dev/mem c 1 1
- chown root:kmem /dev/mem
The file kmem is the same as mem, except that the kernel virtual memory rather than physical memory is accessed. /dev/kmem is typically created by:
- mknod -m 640 /dev/kmem c 1 2
- chown root:kmem /dev/kmem
/dev/port is similar to mem, but the I/O ports are accessed. It is typically created by:
- mknod -m 660 /dev/port c 1 4
- chown root:mem /dev/port
Here is the description on the difference between kmem and mem.