kexec and arm64 advice

Discussion:

Simon T

2016-10-24 14:42:45 UTC

Hi,

I'm trying to get kexec working on a cross-compiled arm64/aarch64
system, using Linux kernel 4.4.23. I'm using kexec-tool's master
branch (commit e345e27417db00a9e754ca0ca14b2ec87d0552f7 from
https://git.kernel.org/cgit/linux/kernel/git/geoff/kexec-tools.git). I
initially tried using the patches for linux-kexec's kexec-13 branch
with manual massaging in some spots because kexec-13 is for 4.4.0 not
4.4.23. Both tools and kernel appear to build fine, however when it
comes time to kexec, I encounter this message: "kexec_load failed:
Function not implemented"

Searching through the patches, I don't find any reference to kexec_load itself.

Should I be applying a different version of kexec-tools, or
linux-kexec patches, to my build? (I'm restricted to 4.4.23 as the
base kernel)

Is there a way post compile to check if the kexec_load function is
implemented, aside from actually deploying the image and calling
kexec? I've run strings against the Image but it doesn't give an exact
match for kexec_load (see below).

Anything else I should be looking at?

# kexec -l /mnt/target/boot/vmlinux --initrd=/tmp/root.sfs
Modified cmdline:root=/dev/mmcblk0p2
Unable to find /proc/device-tree/chosen/[linux,]stdout-path, printing
from purgatory is disabled
kexec_load failed: Function not implemented
entry = 0x8095f000 flags = 0xb70000
nr_segments = 4
segment[0].buf = 0x7fa0f64010
segment[0].bufsz = 0x7fbc00
segment[0].mem = 0x80080000
segment[0].memsz = 0x8d0000
segment[1].buf = 0x20cc0830
segment[1].bufsz = 0xe515
segment[1].mem = 0x80950000
segment[1].memsz = 0xf000
segment[2].buf = 0x20ccf840
segment[2].bufsz = 0x6080
segment[2].mem = 0x8095f000
segment[2].memsz = 0x7000
segment[3].buf = 0x7f9e843010
segment[3].bufsz = 0x2720000
segment[3].mem = 0xc0000000
segment[3].memsz = 0x2720000

(I've also tried kexec -l with boot/Image instead of boot/vmlinux)

$ grep -i kexec .config
CONFIG_KERNEL_KEXEC=y
CONFIG_PACKAGE_kexec-tools=y
CONFIG_KEXEC_TOOLS_TARGET_NAME="aarch64"
# CONFIG_KEXEC_TOOLS_kdump is not set
CONFIG_KEXEC_ZLIB=y
# CONFIG_KEXEC_LZMA is not set

$ strings <build_dir>/arch/arm64/boot/Image | grep kexec_load
Wcompat_sys_kexec_load
Wsys_kexec_load

Thanks!

Simon

Goel, Sameer

2016-10-24 22:53:47 UTC

Permalink

It seems that the kexec_load syscall is not defined. Can you please
check the configs of your running kernel once again?

Thanks,
Sameer

Post by Simon T
Hi,
I'm trying to get kexec working on a cross-compiled arm64/aarch64
system, using Linux kernel 4.4.23. I'm using kexec-tool's master
branch (commit e345e27417db00a9e754ca0ca14b2ec87d0552f7 from
https://git.kernel.org/cgit/linux/kernel/git/geoff/kexec-tools.git). I
initially tried using the patches for linux-kexec's kexec-13 branch
with manual massaging in some spots because kexec-13 is for 4.4.0 not
4.4.23. Both tools and kernel appear to build fine, however when it
Function not implemented"
Searching through the patches, I don't find any reference to kexec_load itself.
Should I be applying a different version of kexec-tools, or
linux-kexec patches, to my build? (I'm restricted to 4.4.23 as the
base kernel)
Is there a way post compile to check if the kexec_load function is
implemented, aside from actually deploying the image and calling
kexec? I've run strings against the Image but it doesn't give an exact
match for kexec_load (see below).
Anything else I should be looking at?
# kexec -l /mnt/target/boot/vmlinux --initrd=/tmp/root.sfs
Modified cmdline:root=/dev/mmcblk0p2
Unable to find /proc/device-tree/chosen/[linux,]stdout-path, printing
from purgatory is disabled
kexec_load failed: Function not implemented
entry = 0x8095f000 flags = 0xb70000
nr_segments = 4
segment[0].buf = 0x7fa0f64010
segment[0].bufsz = 0x7fbc00
segment[0].mem = 0x80080000
segment[0].memsz = 0x8d0000
segment[1].buf = 0x20cc0830
segment[1].bufsz = 0xe515
segment[1].mem = 0x80950000
segment[1].memsz = 0xf000
segment[2].buf = 0x20ccf840
segment[2].bufsz = 0x6080
segment[2].mem = 0x8095f000
segment[2].memsz = 0x7000
segment[3].buf = 0x7f9e843010
segment[3].bufsz = 0x2720000
segment[3].mem = 0xc0000000
segment[3].memsz = 0x2720000
(I've also tried kexec -l with boot/Image instead of boot/vmlinux)
$ grep -i kexec .config
CONFIG_KERNEL_KEXEC=y
CONFIG_PACKAGE_kexec-tools=y
CONFIG_KEXEC_TOOLS_TARGET_NAME="aarch64"
# CONFIG_KEXEC_TOOLS_kdump is not set
CONFIG_KEXEC_ZLIB=y
# CONFIG_KEXEC_LZMA is not set
$ strings <build_dir>/arch/arm64/boot/Image | grep kexec_load
Wcompat_sys_kexec_load
Wsys_kexec_load
Thanks!
Simon
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a Linux Foundation Collaborative Project.

Simon T

2016-10-25 11:59:49 UTC

Permalink

Hi Sameer,

The running kernel and the kernel I am trying to kexec into are the
same -- for testing purposes I'm just trying to kexec into a second
copy of the same kernel I'm running. The .config file has kexec
defined:

$ grep -i kexec .config
CONFIG_KERNEL_KEXEC=y
CONFIG_PACKAGE_kexec-tools=y
CONFIG_KEXEC_TOOLS_TARGET_NAME="aarch64"
# CONFIG_KEXEC_TOOLS_kdump is not set
CONFIG_KEXEC_ZLIB=y
# CONFIG_KEXEC_LZMA is not set

Is there another way to verify if the kernel actually built with the
kexec_load syscall or not?

Thanks,

Simon

It seems that the kexec_load syscall is not defined. Can you please check
the configs of your running kernel once again?
Thanks,
Sameer

--
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.

Geoff Levand

2016-10-25 16:57:29 UTC

Permalink

Post by Simon T
Both tools and kernel appear to build fine, however when it
Function not implemented"

It seems your kernel needs kexec support. Try something like:

cat /proc/config.gz | gunzip | egrep 'KEXEC'

-Geoff

Simon T

2016-10-26 13:52:50 UTC

Permalink

Post by Geoff Levand

Post by Simon T
Both tools and kernel appear to build fine, however when it
Function not implemented"

cat /proc/config.gz | gunzip | egrep 'KEXEC'

Aha, yes you are correct it is not compiled in, even though it was in
my .config. I will investigate my config files and build scripts
further,

Thanks,

Simon