We will have a linux boot option rom soon, so let's take all functionality
that might be useful for both to a header file that both roms can include.
That way we only have to write fw_cfg access code once.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Right now we load the guest kernel to RAM, fire off the BIOS, hope it
doesn't clobber memory and run an option rom that jumps into the kernel.
That breaks with SeaBIOS, as that clears memory. So let's read all
kernel, module etc. data using the fw_cfg interface when in the int19
handler.
This patch implements said mechanism for multiboot.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
On Wed, Sep 23, 2009 at 10:55:02PM +0200, Juergen Lock wrote:
> On Wed, Sep 23, 2009 at 09:31:16PM +0100, Laurence Tratt wrote:
>[...]
> > then the above error doesn't occur, but
> > pc-bios/optionrom/multiboot.S dies as follows:
> >
> > $
> > AS optionrom/multiboot.o
> > multiboot.S: Assembler messages:
> > multiboot.S:116: Error: `%es:-4(%edi)' is not a valid 16 bit base/index
> > expression
> > $
> >
> > What little Intel assembler I ever knew has long since departed from my
> > brain, so I don't know why that error occurs, nor what a fix might be.
> >
> It occurs because of too old binutils (as(1) in this case), on FreeBSD
> we now have a port for newer ones,
> http://www.freshports.org/devel/binutils
> so I depend on that and have the optionrom Makefile use the new as
> like this: (the first change wrt CFLAGS is unrelated and has probably
> been fixed in the meantime; it caused gmake to complain about
> recursive use of CFLAGS.)
>
> Index: qemu/pc-bios/optionrom/Makefile
> @@ -9,10 +9,13 @@
>
> CFLAGS = -Wall -Wstrict-prototypes -Werror -fomit-frame-pointer -fno-builtin
> CFLAGS += -I$(SRC_PATH)
> -CFLAGS += $(call cc-option, $(CFLAGS), -fno-stack-protector,"")
> +CFLAGS := $(CFLAGS) $(call cc-option, $(CFLAGS), -fno-stack-protector,"")
>
> build-all: multiboot.bin
>
> +%.o: %.S
> + $(CC) -E $(CFLAGS) -o - -c $< |${LOCALBASE}/bin/as -V -Qy -o $@
> +
> %.img: %.o
> $(call quiet-command,$(LD) -Ttext 0 -e _start -s -o $@ $<," Building $(TARGET_DIR)$@")
>
That patch didn't seem to help on OpenBSD so I now finally got around
making another one that just emits the bytes of the offending insn
instead so people can keep using old assemblers:
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patch implements support for Multiboot on x86 for -kernel.
Multiboot is a "new" approach to get rid of different bootloaders, providing
a unified interface for the kernel. It supports command line options and
kernel modules.
The two probably best known projects using multiboot are Xen and GNU Hurd.
This implementation should be mostly feature-complete. It is missing VBE
extensions, but as no system uses them currently it does not really hurt.
To use multiboot, specify the kernel as -kernel option. Modules should be given
as -initrd options, seperated by a comma (,). -append also works.
Please bear in mind that grub also does gzip decompression, which qemu does
not do yet. To run existing images, please ungzip them first.
The guest multiboot loader code is implemented as option rom using int 19.
Parts of the work are based on efforts by Rene Rebe, who originally ported
my code to int 19.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
