With all support in place for preserving memory regions, enable fadump by
exporting the "ibm,kernel-dump" property in the device tree, representing
the fadump dump information, in case of a crash.
Currently "ibm,configure-kernel-dump" RTAS call is already registered,
which tells the kernel that the platform (QEMU) supports fadump.
Now, in case of a crash, if fadump was registered, we also pass
"ibm,kernel-dump" in device tree, which tells the kernel that the fadump
dump is active.
Pass "fadump=on" to enable Linux to use firmware assisted dump.
Logs of a linux boot with firmware assisted dump:
$ ./build/qemu-system-ppc64 -M pseries,x-vof=on --cpu power10 --smp 4 -m 4G -kernel some-vmlinux -initrd some-initrd -append "debug fadump=on crashkernel=1G" -nographic
[ 0.000000] fadump: Reserved 1024MB of memory at 0x00000040000000 (System RAM: 4096MB)
[ 0.000000] fadump: Initialized 0x40000000 bytes cma area at 1024MB from 0x400102a8 bytes of memory reserved for firmware-assisted dump
...
[ 1.084686] rtas fadump: Registration is successful!
...
# cat /sys/kernel/debug/powerpc/fadump_region
CPU :[0x00000040000000-0x000000400013df] 0x13e0 bytes, Dumped: 0x0
HPTE:[0x000000400013e0-0x000000400013df] 0x0 bytes, Dumped: 0x0
DUMP: Src: 0x00000000000000, Dest: 0x00000040010000, Size: 0x40000000, Dumped: 0x0 bytes
[0x0000000921a000-0x0000000921a7ff]: cmdline append: ''
# echo c > /proc/sysrq-trigger
The fadump boot after crash:
[ 0.000000] rtas fadump: Firmware-assisted dump is active.
[ 0.000000] fadump: Updated cmdline: debug fadump=on crashkernel=1G
[ 0.000000] fadump: Firmware-assisted dump is active.
[ 0.000000] fadump: Reserving 3072MB of memory at 0x00000040000000 for preserving crash data
....
# file /proc/vmcore
/proc/vmcore: ELF 64-bit LSB core file, 64-bit PowerPC or cisco 7500, OpenPOWER ELF V2 ABI, version 1 (SYSV), SVR4-style
Analysing the vmcore with crash-utility:
KERNEL: vmlinux-6.14-rc2
DUMPFILE: vmcore-fc92fb373aa0
CPUS: 4
DATE: Wed Mar 12 23:39:23 CDT 2025
UPTIME: 00:00:22
LOAD AVERAGE: 0.13, 0.03, 0.01
TASKS: 95
NODENAME: buildroot
RELEASE: 6.12.0-rc4+
VERSION: #1 SMP Fri Jan 3 00:15:17 IST 2025
MACHINE: ppc64le (1000 Mhz)
MEMORY: 4 GB
PANIC: "Kernel panic - not syncing: sysrq triggered crash"
PID: 269
COMMAND: "sh"
TASK: c00000000a050b00 [THREAD_INFO: c00000000a050b00]
CPU: 0
STATE: TASK_RUNNING (PANIC)
Signed-off-by: Aditya Gupta <adityag@linux.ibm.com>
---
hw/ppc/spapr.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 3cbc6a7409b7..f6e666ad4344 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -904,6 +904,9 @@ static void spapr_dt_rtas_fadump(SpaprMachineState *spapr, void *fdt, int rtas)
{
MachineState *ms = MACHINE(spapr);
MachineClass *mc = MACHINE_GET_CLASS(ms);
+ FadumpMemStruct *fdm = &spapr->registered_fdm;
+ uint16_t dump_status_flag;
+ bool is_next_boot_fadump;
uint32_t max_possible_cpus = mc->possible_cpu_arch_ids(ms)->len;
uint64_t fadump_cpu_state_size = 0;
@@ -953,6 +956,18 @@ static void spapr_dt_rtas_fadump(SpaprMachineState *spapr, void *fdt, int rtas)
fadump_versions, sizeof(fadump_versions))));
_FDT((fdt_setprop(fdt, rtas, "ibm,configure-kernel-dump-sizes",
fadump_rgn_sizes, sizeof(fadump_rgn_sizes))));
+
+ dump_status_flag = be16_to_cpu(fdm->header.dump_status_flag);
+ is_next_boot_fadump =
+ (dump_status_flag & FADUMP_STATUS_DUMP_TRIGGERED) != 0;
+ if (is_next_boot_fadump) {
+ uint64_t fdm_size =
+ sizeof(struct FadumpSectionHeader) +
+ (be16_to_cpu(fdm->header.dump_num_sections) *
+ sizeof(struct FadumpSection));
+
+ _FDT((fdt_setprop(fdt, rtas, "ibm,kernel-dump", fdm, fdm_size)));
+ }
}
static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
--
2.49.0