On Fri, Sep 04, 2015 at 02:11:59PM +0200, Michael Holzheu wrote: > The slurp_fd() function allocates memory and uses the read() system call. > This results in double memory consumption for image and initrd: > > 1) Memory allocated in user space by the kexec tool > 2) Memory allocated in kernel by the kexec() system call > > Therefore use mmap() for non-character devices to reduce the runtime > memory consumption of the kexec tool. > > The following use case illustrates the usefulness of this patch a bit more: > > 1) Boot a 4 GB Linux system > 2) Read kernel and 1,5 GB ramdisk from external source into local tmpfs (ram) > 3) kexec the kernel and ramdisk > > Without this patch for the kexec runtime we need: > > 1,5 GB (tmpfs) + 1,5 GB (kexec malloc) + 1,5 GB (kernel memory) = 4,5 GB > > Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com> Thanks, applied.
