Re: [Qemu-devel] [PATCH v6 0/4] allow to load initrd below 4G for recent kernel

[Paolo Bonzini]

On 17/01/19 13:49, Li Zhijian wrote:
> Long long ago, linux kernel has supported up to 4G initrd, but it's header
> still hard code to allow loading initrd below 2G only.
>  cutting from arch/boot/x86/header.S:
>  # (Header version 0x0203 or later) the highest safe address for the contents
>  # of an initrd. The current kernel allows up to 4 GB, but leave it at 2 GB to
>  # avoid possible bootloader bugs.
> 
> In order to support more than 2G initrd, qemu must allow loading initrd
> above 2G address. Luckly, recent kernel introduced a new field to linux header
> named xloadflags:XLF_CAN_BE_LOADED_ABOVE_4G which tells bootloader an optional
> and safe address to load initrd.
> 
> It's believed that if XLF_CAN_BE_LOADED_ABOVE_4G is set, initrd can
> be loaded into any address.
> 
> Default roms(Seabios + optionrom(linuxboot_dma)) works as expected with this
> patchset.
> 
> I stole some comments from yours, fell free to let me know if you don't like 
> this.
> 
> changes:
> V6: no functional changes
>  - Patch 3/4: Fix line over 80 characters && use double quates for all pathes 
> (Stefano Garzarella)
>  - Patch 4/4: update comments
> 
> V5: add a few reviewed-tag and update 4/4 changelog and comments
> V4:
>   - add Reviwed-by tag to 1/4 and 2/4
>   - use scripts/update-linux-headers.sh to import bootparam.h
>   - minor fix at commit log
> V3:
>  - rebase code basing on http://patchwork.ozlabs.org/cover/1005990 and
>    https://patchew.org/QEMU/address@hidden
>  - add new patch 3/4 to import header bootparam.h (Michael S. Tsirkin)
> 
> V2: add 2 patches(3/5, 4/5) to fix potential loading issue.
> 
> 
> CC: Paolo Bonzini <address@hidden>
> CC: Richard Henderson <address@hidden>
> CC: Eduardo Habkost <address@hidden>
> CC: "Michael S. Tsirkin" <address@hidden>
> CC: Marcel Apfelbaum <address@hidden>
> CC: Stefano Garzarella <address@hidden>
> CC: Peter Crosthwaite <address@hidden>
> CC: Peter Maydell <address@hidden>
> 
> Li Zhijian (4):
>   unify len and addr type for memory/address APIs
>   hw/core/loader.c: Read as long as possible in load_image_size()
>   i386: import & use bootparam.h
>   i386: allow to load initrd below 4 GB for recent linux
> 
>  exec.c                                       | 47 
> ++++++++++++++--------------
>  hw/core/loader.c                             | 11 +++----
>  hw/i386/pc.c                                 | 29 ++++++++++++-----
>  include/exec/cpu-all.h                       |  2 +-
>  include/exec/cpu-common.h                    |  8 ++---
>  include/exec/memory.h                        | 22 ++++++-------
>  include/standard-headers/asm-x86/bootparam.h | 34 ++++++++++++++++++++
>  scripts/update-linux-headers.sh              |  6 ++++
>  8 files changed, 105 insertions(+), 54 deletions(-)
>  create mode 100644 include/standard-headers/asm-x86/bootparam.h
> 

Queued, thanks.

Paolo