From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Re: [PATCH 08/15] kexec: New syscall kexec_file_load() declaration Date: Thu, 26 Jun 2014 16:43:03 -0400 Message-ID: <20140626204303.GE11136@redhat.com> References: <1403814824-7587-1-git-send-email-vgoyal@redhat.com> <1403814824-7587-9-git-send-email-vgoyal@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1403814824-7587-9-git-send-email-vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Cc: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org, hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org, mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org, greg-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org, bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org, dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, chaowang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org 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 > CC: linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.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 --- 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 .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 ()