On 01/29/2015 05:06 PM, Scot Doyle wrote: > On Thu, 29 Jan 2015, Michael Kerrisk (man-pages) wrote: >> On 29 January 2015 at 02:27, Scot Doyle <lkml14 at scotdoyle.com> wrote: >>> On Wed, 28 Jan 2015, Vivek Goyal wrote: >>>> On Wed, Jan 28, 2015 at 10:10:59PM +0000, Scot Doyle wrote: >>>>> On Wed, 28 Jan 2015, Vivek Goyal wrote: >>>>>> On Wed, Jan 28, 2015 at 09:14:03PM +0000, Scot Doyle wrote: >>>>>>> When I tested, kexec_file_load required CONFIG_RELOCATABLE. Is the same >>>>>>> true for kexec_load? Would it make sense to note this in the man pages >>>>>>> along with the need for CONFIG_KEXEC_FILE, etc? Or as an error message? >>>>>> >>>>>> Hmm.., I can't see an explicity dependency between RELOCATABLE and >>>>>> KEXEC. Both KEXEC and KEXEC_FILE should be able to load a kernel >>>>>> even if it had RELOCATABLE=n. >>>>>> >>>>>> Just that kernel will run from the address it has been built for. >>>>>> >>>>>> Thanks >>>>>> Vivek >>>>> >>>>> Confusing, right? kexec_file_load returns -ENOEXEC and dmesg says >>>>> "kexec-bzImage64: XLF_CAN_BE_LOADED_ABOVE_4G is not set." which leads to >>>>> arch/x86/boot/header.S line 396: >>>>> >>>>> #if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64) >>>>> /* kernel/boot_param/ramdisk could be loaded above 4g */ >>>>> # define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G >>>>> #else >>>>> # define XLF1 0 >>>>> #endif >>>> >>>> Ah, this one. Actually generic kexec file loading implementation does not >>>> impose this restriction. It is the image specific loader part which >>>> decides what kind of bzImage it can load. >>>> >>>> Current implementation (kexec-bzimage64.c), is only supporting loading >>>> bzImages which are 64bit and can be loaded above 4G. This simplifies >>>> the implementation of loader. >>>> >>>> But there is nothing which prevents one from implementing other image >>>> loaders. >>>> >>>> So instead of saying that kexec_file_load() depends on CONFIG_RELOCATABLE, >>>> it might be better to say in man page that currently this system call >>>> supports only loading a bzImage which is 64bit and which can be loaded >>>> above 4G too. >>>> >>>> Thanks >>>> Vivek >>> >>> Thanks, I agree, and think it would make sense to list them as part of the >>> page's ENOEXEC error. >> >> Scott, could you then phras a couple of sentences that capture thge >> details, so I can add it to the ENOEXEC error? >> >> Thanks, >> >> Michael > > Yes, maybe something like "kernel_fd does not refer to an open file, or > the file type is not supported. Currently, the file must be a bzImage > and contain an x86 kernel loadable above 4G in memory (see > Documentation/x86/boot.txt)."? > > boot.txt explains that loading above 4G implies 64-bit and is specified > via a bit in xloadflags added in Linux 3.8. Added and pushed. Thanks, Scott. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
