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Re: [Qemu-devel] [Xen-devel] [RFC PATCH V3 2/2] qemu: support xen hvm di
From: |
Chun Yan Liu |
Subject: |
Re: [Qemu-devel] [Xen-devel] [RFC PATCH V3 2/2] qemu: support xen hvm direct kernel boot |
Date: |
Sun, 22 Jun 2014 21:36:45 -0600 |
>>> 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
>
>
> > + 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
> >
>
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