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/x86/head.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 bootload an optional
and safe address to load initrd.
Current QEMU/BIOS always loads initrd below below_4g_mem_size which always
less than 4G, so here limiting initrd_max to 4G - 1 simply is enough if
this bit is set.
Default roms(Seabios + optionrom(linuxboot_dma)) works as expected with this
patchset.
changes:
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.
Li Zhijian (4):
unify len and addr type for memory/address APIs
refactor load_image_size
i386: import & use bootparam.h
i386: allow to load initrd below 4G for recent linux
exec.c | 47 ++++++++++++++--------------
hw/core/loader.c | 11 +++----
hw/i386/pc.c | 18 ++++++-----
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 | 4 +++
8 files changed, 92 insertions(+), 54 deletions(-)
create mode 100644 include/standard-headers/asm-x86/bootparam.h