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Message-ID: <1a0bb291-c670-44c3-af7b-d2b5aac51a18@linux.ibm.com>
Date: Sun, 7 Sep 2025 12:27:23 +0530
From: Sourabh Jain <sourabhjain@...ux.ibm.com>
To: Madhavan Srinivasan <maddy@...ux.ibm.com>,
Michael Ellerman <mpe@...erman.id.au>, bcollins@...nel.org
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kexec: Include kernel-end even without crashkernel
On 22/04/25 08:06, Ben Collins wrote:
> Certain versions of kexec don't even work without kernel-end being
> added to the device-tree. Add it even if crash-kernel is disabled.
>
> Signed-off-by: Ben Collins <bcollins@...nel.org>
> Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: linuxppc-dev@...ts.ozlabs.org
> Cc: linux-kernel@...r.kernel.org
> ---
> arch/powerpc/kexec/core.c | 27 +++++++++++++++------------
> 1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/kexec/core.c b/arch/powerpc/kexec/core.c
> index 00e9c267b912f..7b5958c37f702 100644
> --- a/arch/powerpc/kexec/core.c
> +++ b/arch/powerpc/kexec/core.c
> @@ -22,6 +22,8 @@
> #include <asm/setup.h>
> #include <asm/firmware.h>
>
> +#define cpu_to_be_ulong __PASTE(cpu_to_be, BITS_PER_LONG)
> +
> #ifdef CONFIG_CRASH_DUMP
> void machine_crash_shutdown(struct pt_regs *regs)
> {
> @@ -136,17 +138,10 @@ int __init overlaps_crashkernel(unsigned long start, unsigned long size)
> }
>
> /* Values we need to export to the second kernel via the device tree. */
> -static phys_addr_t kernel_end;
> static phys_addr_t crashk_base;
> static phys_addr_t crashk_size;
> static unsigned long long mem_limit;
>
> -static struct property kernel_end_prop = {
> - .name = "linux,kernel-end",
> - .length = sizeof(phys_addr_t),
> - .value = &kernel_end,
> -};
> -
> static struct property crashk_base_prop = {
> .name = "linux,crashkernel-base",
> .length = sizeof(phys_addr_t),
> @@ -165,8 +160,6 @@ static struct property memory_limit_prop = {
> .value = &mem_limit,
> };
>
> -#define cpu_to_be_ulong __PASTE(cpu_to_be, BITS_PER_LONG)
> -
> static void __init export_crashk_values(struct device_node *node)
> {
> /* There might be existing crash kernel properties, but we can't
> @@ -190,6 +183,15 @@ static void __init export_crashk_values(struct device_node *node)
> mem_limit = cpu_to_be_ulong(memory_limit);
> of_update_property(node, &memory_limit_prop);
> }
> +#endif /* CONFIG_CRASH_RESERVE */
> +
> +static phys_addr_t kernel_end;
> +
> +static struct property kernel_end_prop = {
> + .name = "linux,kernel-end",
> + .length = sizeof(phys_addr_t),
> + .value = &kernel_end,
> +};
>
> static int __init kexec_setup(void)
> {
> @@ -200,16 +202,17 @@ static int __init kexec_setup(void)
> return -ENOENT;
>
> /* remove any stale properties so ours can be found */
> - of_remove_property(node, of_find_property(node, kernel_end_prop.name, NULL));
> + of_remove_property(node, of_find_property(node, kernel_end_prop.name,
> + NULL));
>
> /* information needed by userspace when using default_machine_kexec */
> kernel_end = cpu_to_be_ulong(__pa(_end));
> of_add_property(node, &kernel_end_prop);
>
> +#ifdef CONFIG_CRASH_RESERVE
> export_crashk_values(node);
> -
> +#endif
> of_node_put(node);
> return 0;
> }
> late_initcall(kexec_setup);
> -#endif /* CONFIG_CRASH_RESERVE */
While cleaning up KEXEC and KDUMP configs, the export linux,kernel-end
was moved under CONFIG_CRASH_DUMP.
commit 5c4233cc0920cc90787aafe950b90f6c57a35b88 (HEAD, tag: powerpc-6.9-2)
Author: Hari Bathini <hbathini@...ux.ibm.com>
Date: Mon Feb 26 16:00:10 2024 +0530
powerpc/kdump: Split KEXEC_CORE and CRASH_DUMP dependency
So, if kexec is enabled without CONFIG_CRASH_DUMP, the kexec command
fails to load the kexec kernel using the `kexec_load` system call.
[root]# kexec --initrd=/boot/initramfs-`uname -r`.img
/boot/vmlinuz-`uname -r` --append="`cat /proc/cmdline`" -lcd
Try gzip decompression.
Try LZMA decompression.
kernel: 0x7fffaef30010 kernel_size: 0x2ccba80
0000000000000000-0000000030000000 : 0
0000000030000000-0000004000000000 : 0
get base memory ranges:2
/proc/device-tree/chosen/linux,kernel-end: No such file or directory
Could not get memory layout
[root]# echo $?
255
So, it is better to call kexec_setup/kexec/core.c even when
CONFIG_CRASH_DUMP is not enabled and export linux,kernel-end, because kexec
requires this to load the kexec kernel using the kexec_file_load system
call.
I suggest adding a Fixes tag to the commit I mentioned above and also
including the logs I shared. That might help others discover
this fix if they run into the same issue.
Rest look good to me.
Reviewed-by: Sourabh Jain <sourabhjain@...ux.ibm.com>
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