Re: [Qemu-devel] [PATCH v4.1] Add optionrom compatible with fw_cfg DMA version

["Marc Marí" <marc.mari.barcelo@gmail.com>]

On Mon, 4 Apr 2016 16:02:04 +0100
Stefan Hajnoczi <stefanha@gmail.com> wrote:

> On Fri, Apr 01, 2016 at 01:43:47PM +0100, Richard W.M. Jones wrote:
> > From: Marc Marí <markmb@redhat.com>
> > 
> > This optionrom is based on linuxboot.S.
> > 
> > Signed-off-by: Marc Marí <markmb@redhat.com>
> > Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
> > ---
> >  .gitignore                        |   4 +
> >  hw/i386/pc.c                      |   9 +-
> >  hw/nvram/fw_cfg.c                 |   2 +-
> >  include/hw/nvram/fw_cfg.h         |   1 +
> >  pc-bios/optionrom/Makefile        |   7 +-
> >  pc-bios/optionrom/linuxboot_dma.c | 297
> > ++++++++++++++++++++++++++++++++++++++ 6 files changed, 315
> > insertions(+), 5 deletions(-) create mode 100644
> > pc-bios/optionrom/linuxboot_dma.c  
> 
> It would be great to merge this but there's more work necessary.
> 
> I CCed Marc's current email address.  He was interning at Red Hat but
> is now back at university so the Red Hat address is not being read.
> 
> Marc: What was still missing from this patch?

I'm sorry I have not answered before, it's been a very busy week.

What's missing (as I remember it):
 - Debug loading an initrd from the new linuxboot
 - Other minor comments in the thread (mainly, compile using mingw).
 - Make it possible to disable DMA fw_cfg.

I've been putting this patch at the back of my todo list for too long.
Let me address some deadlines for this week, and then I'll finish this
patch.

Marc
 
> > diff --git a/pc-bios/optionrom/Makefile b/pc-bios/optionrom/Makefile
> > index ce4852a..bdd0cc1 100644
> > --- a/pc-bios/optionrom/Makefile
> > +++ b/pc-bios/optionrom/Makefile
> > @@ -13,15 +13,18 @@ CFLAGS := -Wall -Wstrict-prototypes -Werror
> > -fomit-frame-pointer -fno-builtin CFLAGS += -I$(SRC_PATH)
> >  CFLAGS += $(call cc-option, $(CFLAGS), -fno-stack-protector)
> >  CFLAGS += $(CFLAGS_NOPIE)
> > +CFLAGS += -m32
> >  QEMU_CFLAGS = $(CFLAGS)
> >  
> > -build-all: multiboot.bin linuxboot.bin kvmvapic.bin
> > +ASFLAGS += -32
> > +
> > +build-all: multiboot.bin linuxboot.bin linuxboot_dma.bin
> > kvmvapic.bin 
> >  # suppress auto-removal of intermediate files
> >  .SECONDARY:
> >  
> >  %.img: %.o
> > -	$(call quiet-command,$(LD) $(LDFLAGS_NOPIE) -Ttext 0 -e
> > _start -s -o $@ $<,"  Building $(TARGET_DIR)$@")
> > +	$(call quiet-command,$(LD) $(LDFLAGS_NOPIE) -m elf_i386
> > -Ttext 0 -e _start -s -o $@ $<,"  Building $(TARGET_DIR)$@")  
> 
> Gerd noted in <1454411187.9300.54.camel@redhat.com>:
> 
>   Hmm, that breaks the windows cross build:
> 
>   make: Entering directory `/home/kraxel/projects/qemu/build-win32'
>   Building optionrom/linuxboot_dma.img
>   i686-w64-mingw32-ld: unrecognised emulation mode: elf_i386
>   Supported emulations: i386pe
>   make[1]: *** [linuxboot_dma.img] Error 1
> 
> and then:
> 
>   Testing shows two more problems:
> 
>   (1) initrd loading is broken, kernel complains it finds only
> gibberish:
> 
>   [    0.934582] Unpacking initramfs...
>   [    1.166983] Initramfs unpacking failed: junk in compressed
> archive [    1.168458] Freeing initrd memory: 32812k freed
> 
>   (2) going back to non-dma boot via -M pc-$old doesn't work,
> appearently fw_cfg dma is enabled even for old machine types.