On Mon, Jul 04, 2011 at 07:09:22PM +0200, Michael Holzheu wrote: > This patch series adds kdump support for the s390 architecture (64 bit). There > are a few common code changes necessary because the s390 implementation is > different to other architectures in some points. Especially these common code > patches (1-7) should be reviewed. Patch 8 "s390: kdump backend code" contains > the s390 specific part. Patch 9 includes the necessary changes for the kexec > tool. > > In the following I describe the main differences of the s390 implementation: > > The s390 kernel is not relocatable therefore the crashkernel memory is swapped > with the area [0 - crashkernel memory] before the kdump kernel is started. > Architectures other than s390 run the kdump kernel at a memory location that is > disjunct to the standard location for the kernel image and to all memory that > might be in use for I/O by the production system. The main reason for this > seems to be that these architectures do not have a means to clear all ongoing > I/O. If active memory of the production system is reused by the kdump kernel > they run into memory corruption issues. On s390 with diagnose call 308 or boot > (IPL) there is the possibility to stop all ongoing I/O. Therefore we can safely > run the kdump kernel at the old location. > > On s390 we do not create page tables for the crashkernel memory and use a > memcpy_real() function to load the kdump kernel and ramdisk in kexec_load() > system call. > > On s390 we have external kdump triggers. For example stand-alone dump tools. > The address range information of crashkernel memory is stored at a well defined > storage location that can be used by the external dump triggers to find the > kdump entry point. To export the address range for the crashkernel memory we > introduce a new mechanism that we call meminfo. This allows to define checksum > secured information in memory that is accessible via an s390 ABI defined > storage address. The following information is currently stored via meminfo: > * Crashkernel memory range > * kexec segments for kdump > * Pointer to vmcoreinfo note I don't understand what is stand-alone dump tools and why the existing mechanism of preparing ELF headers to describe all the above info and just passing the address of header on kernel commnad line (crashkernel=) will not work for s390. Introducing an entirely new infrastructure for communicating the same information does not sound too exciting. Thanks Vivek
