Hello Vivek,
For s390 we want to use /proc/vmcore for our SCSI stand-alone
dump (zfcpdump). We have support where the first HSA_SIZE bytes are
saved into a hypervisor owned memory area (HSA) before the kdump
kernel is booted. When the kdump kernel starts, it is restricted
to use only HSA_SIZE bytes.
The advantages of this mechanism are:
* No crashkernel memory has to be defined in the old kernel.
* Early boot problems (before kexec_load has been done) can be dumped
* Non-Linux systems can be dumped.
We modify the s390 copy_oldmem_page() function to read from the HSA memory
if memory below HSA_SIZE bytes is requested.
Since we cannot use the kexec tool to load the kernel in this scenario,
we have to build the ELF header in the 2nd (kdump/new) kernel.
So with the following patch set we would like to introduce the new
function that the ELF header for /proc/vmcore can be created in the 2nd
kernel memory.
The following steps are done during zfcpdump execution:
1. Production system crashes
2. User boots a SCSI disk that has been prepared with the zfcpdump tool
3. Hypervisor saves CPU state of boot CPU and HSA_SIZE bytes of memory into HSA
4. Boot loader loads kernel into low memory area
5. Kernel boots and uses only HSA_SIZE bytes of memory
6. Kernel saves registers of non-boot CPUs
7. Kernel does memory detection for dump memory map
8. Kernel creates ELF header for /proc/vmcore
9. /proc/vmcore uses this header for initialization
10. The zfcpdump user space reads /proc/vmcore to write dump to SCSI disk
- copy_oldmem_page() copies from HSA for memory below HSA_SIZE
- copy_oldmem_page() copies from real memory for memory above HSA_SIZE
Jan Willeke (1):
s390/kdump: Use ELFCORE_ADDR_NEWMEM for zfcpdump
Michael Holzheu (3):
kdump: Introduce ELFCORE_ADDR_NEWMEM
s390/kdump: Use ELFCORE_ADDR_NEWMEM for kdump
kdump: Merge set_vmcore_list_offsets_elf64/elf32/newmem
arch/s390/Kconfig | 3 +-
arch/s390/include/asm/sclp.h | 1 +
arch/s390/kernel/crash_dump.c | 103 +++++++++++++++++++++++++++---------------
arch/s390/kernel/setup.c | 2 +-
drivers/s390/char/zcore.c | 6 +--
fs/proc/vmcore.c | 89 ++++++++++++++++++++++--------------
include/linux/crash_dump.h | 4 +-
7 files changed, 131 insertions(+), 77 deletions(-)
--
1.8.1.6
