Hi John, See below. eric On 12/16/19 2:54 PM, John Donnelly wrote:
On Dec 16, 2019, at 2:32 PM, Eric DeVolder <eric.devolder@xxxxxxxxxx> wrote: The --command-line, --append, and --reuse-cmdline options to kexec can be used in combination to craft a kernel command line for a kernel loaded via kexec. In addition, the kexec tool may also manipulate further the command line, eg. elfcorehdr addition. To aid in debugging kdump/kexec related issues, it would be helpful for kexec to print the final constructed kernel command line argument. For example, the following simple change (for i386/x86_64): diff --git a/kexec/arch/i386/x86-linux-setup.c b/kexec/arch/i386/x86-linux-setup.c index 057ee14..6dc4adc 100644 --- a/kexec/arch/i386/x86-linux-setup.c +++ b/kexec/arch/i386/x86-linux-setup.c @@ -57,6 +57,8 @@ void setup_linux_bootloader_parameters_high( char *cmdline_ptr; unsigned long initrd_base, initrd_addr_max; + printf("Final kernel cmdline: '%s'\n", cmdline); + /* Say I'm a boot loader */ real_mode->loader_type = LOADER_TYPE_KEXEC << 4; results in the following on a systemd-based system (formatted to fit in 70 char lines): % systemctl status -l kdump.service ● kdump.service - Crash recovery kernel arming Loaded: loaded (/usr/lib/systemd/system/kdump.service; enabled; vendor preset: enabled) Active: active (exited) since Mon 2019-12-16 14:59:21 EST; 2min 53s ago Process: 14058 ExecStop=/usr/bin/kdumpctl stop (code=exited, status=0/SUCCESS) Process: 14073 ExecStart=/usr/bin/kdumpctl start (code=exited, status=0/SUCCESS) Main PID: 14073 (code=exited, status=0/SUCCESS) Dec 16 14:59:18 vm364 kdumpctl[14058]: Stopping kdump: [OK] Dec 16 14:59:18 vm364 systemd[1]: Stopped Crash recovery kernel arming. Dec 16 14:59:18 vm364 systemd[1]: Starting Crash recovery kernel arming... Dec 16 14:59:21 vm364 kdumpctl[14073]: Final kernel cmdline: 'BOOT_IMAGE= /vmlinuz-4.14.35-1902.7.3.1.el7uek.x86_64 ro rhgb quiet LANG=en_US.UTF-8 irqpoll nr_cpus=1 reset_devices cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail acpi_no_memhotplug transparent_hugepage=never nokaslr novmcoredd disable_cpu_apicid=0 elfcorehdr=901492K' Dec 16 14:59:21 vm364 systemd[1]: Started Crash recovery kernel arming. Dec 16 14:59:21 vm364 kdumpctl[14073]: kexec: loaded kdump kernel Dec 16 14:59:21 vm364 kdumpctl[14073]: Starting kdump: [OK] and the output is also available in /var/log/messages. There might also be an opportunity to consolidate handling of the kernel command line, as most arch targets have the --command-line, --append, and --reuse-cmdline options, though each arch independently codes the support for these options. Note: Simply printing the cmdline in scripts such as kdumpctl may not result in the same ordering, and will omit any addition made internally by kexec, such as the elfcorehdr. I propose the addition of an option to kexec, --print-kcl (to mirror --print-ckr), that would control such printing, as well as the needed per arch conditional print statements similar to the above to print the final constructed kernel command line.Is this common code available in the Arm environment too ?
The option would be in common code.
If not, could you make it so ?
I'm not sure, yet, as to what degree of consolidation of the --command-line --append and --resuse-cmdline options into common code is desirable.
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