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    SubjectRe: Edited kexec_load(2) [kexec_file_load()] man page for review
    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.


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