On Thu, Jun 26, 2014 at 04:33:37PM -0400, Vivek Goyal wrote:
> This is the new syscall kexec_file_load() declaration/interface. I have
> reserved the syscall number only for x86_64 so far. Other architectures
> (including i386) can reserve syscall number when they enable the support
> for this new syscall.
>
> Signed-off-by: Vivek Goyal <vgoyal at redhat.com>
> CC: linux-api at vger.kernel.org
Hi Michael,
As per feedback last time, I enhanced the existing man page to include
details of this new syscall. Here is the patch.
Thanks
Vivek
Subject: kexec_file_load() syscall man page
We already have man page for kexec_load() syscall. This patch adds details
of kexec_file_load() to same man page.
Signed-off-by: Vivek Goyal <vgoyal at redhat.com>
---
man2/kexec_file_load.2 | 1
man2/kexec_load.2 | 55 +++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 50 insertions(+), 6 deletions(-)
Index: man-pages/man2/kexec_file_load.2
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ man-pages/man2/kexec_file_load.2 2014-06-25 17:39:12.056441803 -0400
@@ -0,0 +1 @@
+.so man2/kexec_load.2
Index: man-pages/man2/kexec_load.2
===================================================================
--- man-pages.orig/man2/kexec_load.2 2014-06-25 17:36:09.237453355 -0400
+++ man-pages/man2/kexec_load.2 2014-06-26 11:11:49.599810213 -0400
@@ -25,17 +25,26 @@
.\"
.TH KEXEC_LOAD 2 2012-07-13 "Linux" "Linux Programmer's Manual"
.SH NAME
-kexec_load \- load a new kernel for later execution
+kexec_load, kexec_file_load \- load a new kernel for later execution
.SH SYNOPSIS
.B #include <linux/kexec.h>
.br
+
.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments ","
.br
.BI " struct kexec_segment *" segments \
", unsigned long " flags ");"
+.br
+
+.BI "int kexec_file_load(int " kernel_fd ", int " initrd_fd ","
+.br
+.BI " unsigned long " cmdline_len \
+", const char *" cmdline ","
+.br
+.BI " unsigned long " flags ");"
.IR Note :
-There is no glibc wrapper for this system call; see NOTES.
+There are no glibc wrappers for these system calls; see NOTES.
.SH DESCRIPTION
The
.BR kexec_load ()
@@ -111,11 +120,42 @@ struct kexec_segment {
The kernel image defined by
.I segments
is copied from the calling process into previously reserved memory.
+.SS kexec_file_load()
+The
+.BR kexec_file_load ()
+system call is similar to
+.BR kexec_load(),
+but it takes a different set of arguments. It reads kernel to be loaded from
+file descriptor
+.IR kernel_fd
+and initrd to be loaded from file descriptor
+.IR initrd_fd .
+It also takes length of kernel command line in
+.IR cmdline_len
+and pointer to command line in
+.IR cmdline .
+
+The
+.IR flags
+argument is a mask which allows control over system call operation. The
+following values can be specified in
+.IR flags
+
+.TP
+.BR KEXEC_FILE_UNLOAD
+Unload currently loaded kernel.
+.TP
+.BR KEXEC_FILE_ON_CRASH
+Load kernel in memory region reserved for crash kernel. This kernel is
+booted into if currently running kernel crashes.
+.TP
+.BR KEXEC_FILE_NO_INITRAMFS
+Loading initrd/initramfs is optional. Specify this flag if no initramfs
+is being loaded. If this flag is set, kernel will ignore the value passed
+in
+.IR initrd_fd
.SH RETURN VALUE
-On success,
-.BR kexec_load ()
-returns 0.
-On error, \-1 is returned and
+On success, these system calls returns 0. On error, \-1 is returned and
.I errno
is set to indicate the error.
.SH ERRORS
@@ -135,6 +175,9 @@ is too large
The caller does not have the
.BR CAP_SYS_BOOT
capability.
+.TP
+.B ENOEXEC
+kernel_fd does not refer to an open file. Or kernel can't load this file.
.SH VERSIONS
The
.BR kexec_load ()
