Re: [PATCH v7 00/27] x86, boot, 64bit: Add support for loadingramdisk and bzImage above 4G

[Konrad Rzeszutek Wilk]

On Mon, Dec 17, 2012 at 11:15:32PM -0800, Yinghai Lu wrote:
> Now we have limit kdump reseved under 896M, because kexec has the limitation.
> and also bzImage need to stay under 4g.
> 
> To make kexec/kdump could use range above 4g, we need to make bzImage and
> ramdisk could be loaded above 4g.
> During booting bzImage will be unpacked on same postion and stay high.
> 
> The patches add fields in setup_header and boot_params to
> 1. get info about ramdisk position info above 4g from bootloader/kexec
> 2. get info about cmd_line_ptr info above 4g from bootloader/kexec
> 3. set xloadflags bit0 in header for bzImage and bootloader/kexec load
>    could check that to decide if it could to put bzImage high.
> 4. use sentinel to make sure ext_* fields in boot_params could be used.
> 
> This patches is tested with kexec tools with local changes and they are sent
> to kexec list later.
> 
> could be found at:
> 
>         git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-x86-boot

Did a light test and it looks to work under Xen - thought I had not tested
any various configuration of memory layouts. 

More worryingly it blew up under native under an Dell T105 AMD box with 4GB of memory.
I can't get it even to print anything on the serial log:

(this is an excerpt from pxelinux.cfg/C0A8 file)
LABEL BAREMETAL
   KERNEL vmlinuz
   APPEND initrd=initramfs.cpio.gz debug selinux=0  loglevel=10 apic=debug console=uart8250,115200n8


PXELINUX 3.82 2009-06-09  Copyright (C) 1994-2009 H. Peter Anvin et al
Loading vmlinuz.......................................................................
Loading initramfs.cpio.gz.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ready.

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