On Tue, Apr 17, 2018 at 10:01:13AM +0100, Russell King wrote: > On Tue, Apr 17, 2018 at 10:20:08AM +0530, Bhupesh Sharma wrote: > > Hi, > > > > I was working on improving documentation/structure of the upstream > > kexec-tools and I was wondering what is the purpose of the 'kdump' > > directory inside the kexec-tools. > > > > This kdump utility seems to cause confusion with the 'kdump' utility > > present inside some distributions (for e.g. '/usr/sbin/kdump' present > > inside fedora) due to the same naming convention and so we should > > populate/modify the kdump man page to indicate the same, so as to > > avoid confusion. > > > > Presently here are the contents of this directory: > > > > # ls kdump/ > > kdump.8 kdump.c Makefile > > > > - Out of these the kdump man documentation (kdump.8) is just a > > placeholder as suggested by the man page documentation: "kdump - This > > is just a placeholder until real man page has been written" > > > > - Looking at kdump.c : > > > > 1. I understand that this code is mainly used to read a crashdump from > > memory. One can run the same using: > > > > # kdump <start_addr> > > > > where start_addr is basically the start address of the core dump > > (which can also be represented via the 'elfcorehdr' environment > > variable being passed to the crash kernel which represents the > > physical address of the start of the ELF header) > > > > 2. This tool needs READ_ONLY access to /dev/mem (so we need to set > > CONFIG_STRICT_DEVMEM configuration option accordingly). > > > > 3. The code thereafter reads (via mmap) and verifies the ELF header. > > Subsequently it reads (via mmap) the program header. > > > > 4. Then we collect all the notes and write on STDOUT all the headers > > and notes found in the crashdump collected from memory. > > > > So, as per my understanding even in absence of (more powerful) tools > > like crash (or gdb), we can still go ahead and read the crashdump from > > memory and display all the headers and notes present in the same on > > standard serial out interface using this kdump utility. > > > > This is probably a good to have feature for systems which have very > > simple/minimal rootfs (and I see that a few arm32 systems seem to use > > the same as well) or are low on memory availability. > > > > Now, I wanted to confirm if the 'kdump' utility for reading crashdump > > collected from memory is still needed (as the last commit is dated > > back to 2016 and was done for arm32 systems). If yes, I can go ahead > > and enhance the kdump man page to include the description given above > > - so that it helps users understand how to run the tool. > > > > Please share your opinions. > > Firstly, please use: > > git://git.armlinux.org.uk/~rmk/kexec-tools.git > > for ARM systems - this has some important fixes that aren't in the > mainline repository. I apologise if this is due to omission on my part, can we work towards getting them in the mainline repository? _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
