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Re: [Qemu-devel] [Xen-devel] [RFC PATCH V3 2/2] qemu: support xen hvm di
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [Xen-devel] [RFC PATCH V3 2/2] qemu: support xen hvm direct kernel boot |
Date: |
Mon, 23 Jun 2014 11:14:02 +0100 |
User-agent: |
Alpine 2.02 (DEB 1266 2009-07-14) |
On Sun, 22 Jun 2014, Chun Yan Liu wrote:
> >>> On 6/20/2014 at 08:08 PM, in message
> <address@hidden>, Stefano
> Stabellini <address@hidden> wrote:
> > On Fri, 20 Jun 2014, Chunyan Liu wrote:
> > > qemu side patch to support xen HVM direct kernel boot:
> > > if -kernel exists, calls xen_load_linux(), which will read kernel/initrd
> > > and add a linuxboot.bin or multiboot.bin option rom. The
> > > linuxboot.bin/multiboot.bin will load kernel/initrd and jump to execute
> > > kernel directly. It's working when xen uses seabios.
> > >
> > > Signed-off-by: Chunyan Liu <address@hidden>
> > > ---
> > > hw/i386/pc.c | 22 ++++++++++++++++++++++
> > > hw/i386/pc_piix.c | 7 +++++++
> > > hw/i386/xen/xen_apic.c | 1 +
> > > include/hw/i386/pc.h | 5 +++++
> > > 4 files changed, 35 insertions(+)
> > >
> > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > > index 3e0ecf1..e005136 100644
> > > --- a/hw/i386/pc.c
> > > +++ b/hw/i386/pc.c
> > > @@ -1183,6 +1183,28 @@ void pc_acpi_init(const char *default_dsdt)
> > > }
> > > }
> > >
> > > +FWCfgState *xen_load_linux(const char *kernel_filename,
> > > + const char *kernel_cmdline,
> > > + const char *initrd_filename,
> > > + ram_addr_t below_4g_mem_size,
> > > + PcGuestInfo *guest_info)
> > > +{
> > > + int i;
> > > + FWCfgState *fw_cfg;
> > > +
> > > + assert(kernel_filename != NULL);
> > > +
> > > + fw_cfg = fw_cfg_init(BIOS_CFG_IOPORT, BIOS_CFG_IOPORT + 1, 0, 0);
> >
> > Is it actually OK to initialize just BIOS_CFG_IOPORT and avoid
> > everything else currently done in bochs_bios_init?
> > Would it make sense to simply call bochs_bios_init?
> >
> >
> > > + rom_set_fw(fw_cfg);
> > > +
> > > + load_linux(fw_cfg, kernel_filename, initrd_filename, kernel_cmdline,
> > >
> > below_4g_mem_size);
> > > + for (i = 0; i < nb_option_roms; i++) {
> > > + rom_add_option(option_rom[i].name, option_rom[i].bootindex);
> > > + }
> >
> > Wouldn't this have the unintended consequence of possibly loading other
> > option_roms into the guest memory?
>
> For xen, no.
>
> Before this patch, indeed there is another option_rom "kvmvapic" in the list,
> but since the option_rom list is never loaded in xen case, that won't harm.
> But
> as expected, I think in xen case, it should not be in option_rom list at all,
> since
> we won't expect to load it. In v1, I tried to check the option_rom name to
> bypass it and load multiboot.bin/linuxboot.bin only.
>
> In comments, Paolo Bonzini suggests a better way, that is to add following
> line
> in xen_apic_realize():
> + s->vapic_control = 0;
> In this way, "kvmvapic" won't be added to the option_rom list. I think that
> should be the normal way for xen.
>
> So, since V2, I updated in this way.
> http://lists.gnu.org/archive/html/qemu-devel/2014-06/msg00704.html
I see. Paolo's suggestion is a good one.
I would add an assert here to ensure that there is only one option
rom named "linuxboot.bin", so that we can easily spot if something in
the future breaks our assumptions.
> >
> >
> > > + guest_info->fw_cfg = fw_cfg;
> > > + return fw_cfg;
> > > +}
> > > +
> > > FWCfgState *pc_memory_init(MemoryRegion *system_memory,
> > > const char *kernel_filename,
> > > const char *kernel_cmdline,
> > > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > > index a48e263..b737868 100644
> > > --- a/hw/i386/pc_piix.c
> > > +++ b/hw/i386/pc_piix.c
> > > @@ -158,6 +158,13 @@ static void pc_init1(MachineState *machine,
> > > machine->initrd_filename,
> > > below_4g_mem_size, above_4g_mem_size,
> > > rom_memory, &ram_memory, guest_info);
> > > + } else if (machine->kernel_filename != NULL) {
> > > + /* For xen HVM direct kernel boot, load linux here */
> > > + fw_cfg = xen_load_linux(machine->kernel_filename,
> > > + machine->kernel_cmdline,
> > > + machine->initrd_filename,
> > > + below_4g_mem_size,
> > > + guest_info);
> > > }
> > >
> > > gsi_state = g_malloc0(sizeof(*gsi_state));
> > > diff --git a/hw/i386/xen/xen_apic.c b/hw/i386/xen/xen_apic.c
> > > index 63bb7f7..f5acd6a 100644
> > > --- a/hw/i386/xen/xen_apic.c
> > > +++ b/hw/i386/xen/xen_apic.c
> > > @@ -40,6 +40,7 @@ static void xen_apic_realize(DeviceState *dev, Error
> > **errp)
> > > {
> > > APICCommonState *s = APIC_COMMON(dev);
> > >
> > > + s->vapic_control = 0;
> > > memory_region_init_io(&s->io_memory, OBJECT(s), &xen_apic_io_ops, s,
> > > "xen-apic-msi", APIC_SPACE_SIZE);
> >
> > Why this change? It is not mentioned in the commit message.
> >
> >
> > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> > > index ca7a0bd..171a597 100644
> > > --- a/include/hw/i386/pc.h
> > > +++ b/include/hw/i386/pc.h
> > > @@ -134,6 +134,11 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t
> > below_4g_mem_size,
> > > void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
> > > MemoryRegion *pci_address_space);
> > >
> > > +FWCfgState *xen_load_linux(const char *kernel_filename,
> > > + const char *kernel_cmdline,
> > > + const char *initrd_filename,
> > > + ram_addr_t below_4g_mem_size,
> > > + PcGuestInfo *guest_info);
> > > FWCfgState *pc_memory_init(MemoryRegion *system_memory,
> > > const char *kernel_filename,
> > > const char *kernel_cmdline,
> > > --
> > > 1.8.4.5
> > >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > address@hidden
> > http://lists.xen.org/xen-devel
> >
> >
>