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/20181122133507.30950-1-peter.mayd...@linaro.org - 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 <pbonz...@redhat.com> CC: Richard Henderson <r...@twiddle.net> CC: Eduardo Habkost <ehabk...@redhat.com> CC: "Michael S. Tsirkin" <m...@redhat.com> CC: Marcel Apfelbaum <marcel.apfelb...@gmail.com> CC: Stefano Garzarella <sgarz...@redhat.com> CC: Peter Crosthwaite <crosthwaite.pe...@gmail.com> CC: Peter Maydell <peter.mayd...@linaro.org> 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 -- 2.7.4
