On Mon, 2014-06-09 at 17:37 +0200, Igor Mammedov wrote:
> On Mon, 09 Jun 2014 18:10:27 +0300
> Marcel Apfelbaum <marce...@redhat.com> wrote:
>
> > Hi,
> >
> > On Mon, 2014-06-09 at 17:38 +0300, Michael S. Tsirkin wrote:
> > > On Mon, Jun 09, 2014 at 10:20:57AM -0400, Don Slutz wrote:
> > > > On 06/08/14 11:40, Michael S. Tsirkin wrote:
> > > > >On Fri, Jun 06, 2014 at 01:52:05PM -0400, Don Slutz wrote:
> > > > >>This is a pc & q35 only machine opt. One use is to allow for more
> > > > >>ram in a 32bit guest for example:
> > > > >>
> > > > >>-machine pc,max-ram-below-4g=3.75G
> > > > >>
> > > > >>If you add enough PCI devices then all mmio for them will not fit
> > > > >>below 4G which may not be the layout the user wanted. This allows
> > > > >>you to increase the below 4G address space that PCI devices can use
> > > > >>(aka decrease ram below 4G) and therefore in more cases not have any
> > > > >>mmio that is above 4G.
> > > > >>
> > > > >>For example using "-machine pc,max-ram-below-4g=2G" on the command
> > > > >>line will limit the amount of ram that is below 4G to 2G.
> > > > >>
> > > > >>Signed-off-by: Don Slutz <dsl...@verizon.com>
> > > > >>---
> > > > >>v5:
> > > > >> Re-work based on:
> > > > >>
> > > > >> https://github.com/imammedo/qemu/commits/memory-hotplug-v11
> > > > >>
> > > > >>
> > > > >> hw/i386/pc.c | 38 ++++++++++++++++++++++++++++++++++++++
> > > > >> hw/i386/pc_piix.c | 15 ++++++++++++---
> > > > >> hw/i386/pc_q35.c | 15 ++++++++++++---
> > > > >> include/hw/i386/pc.h | 3 +++
> > > > >> vl.c | 4 ++++
> > > > >> 5 files changed, 69 insertions(+), 6 deletions(-)
> > > > >>
> > > > >>diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > > > >>index 7cdba10..bccb746 100644
> > > > >>--- a/hw/i386/pc.c
> > > > >>+++ b/hw/i386/pc.c
> > > > >>@@ -1644,11 +1644,49 @@
> > > > >>pc_machine_get_hotplug_memory_region_size(Object *obj, Visitor *v,
> > > > >>void *opaque,
> > > > >> visit_type_int(v, &value, name, errp);
> > > > >> }
> > > > >>+static void pc_machine_get_max_ram_below_4g(Object *obj, Visitor *v,
> > > > >>+ void *opaque, const char
> > > > >>*name,
> > > > >>+ Error **errp)
> > > > >>+{
> > > > >>+ PCMachineState *pcms = PC_MACHINE(obj);
> > > > >>+ uint64_t value = pcms->max_ram_below_4g;
> > > > >>+
> > > > >>+ visit_type_size(v, &value, name, errp);
> > > > >>+}
> > > > >>+
> > > > >>+static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
> > > > >>+ void *opaque, const char
> > > > >>*name,
> > > > >>+ Error **errp)
> > > > >>+{
> > > > >>+ PCMachineState *pcms = PC_MACHINE(obj);
> > > > >>+ Error *error = NULL;
> > > > >>+ uint64_t value;
> > > > >>+
> > > > >>+ visit_type_size(v, &value, name, &error);
> > > > >>+ if (error) {
> > > > >>+ error_propagate(errp, error);
> > > > >>+ return;
> > > > >>+ }
> > > > >>+ if (value > (1ULL << 32)) {
> > > > >>+ error_set(&error, ERROR_CLASS_GENERIC_ERROR,
> > > > >>+ "Machine option 'max-ram-below-4g=%"PRIu64
> > > > >>+ "' expects size less then or equal to 4G", value);
> > > > >less than
> > > >
> > > > But the test is greater then. So "not greater then" is "less then or
> > > > equal".
> > > > Or did you want the test changed?
> > >
> > > No, just correcting English: less than, not less then :)
> > >
> > > > >>+ error_propagate(errp, error);
> > > > >>+ return;
> > > > >>+ }
> > > > >>+
> > > > >>+ pcms->max_ram_below_4g = value;
> > > > >>+}
> > > > >>+
> > > > >> static void pc_machine_initfn(Object *obj)
> > > > >> {
> > > > >> object_property_add(obj, PC_MACHINE_MEMHP_REGION_SIZE, "int",
> > > > >> pc_machine_get_hotplug_memory_region_size,
> > > > >> NULL, NULL, NULL, NULL);
> > > > >>+ object_property_add(obj, PC_MACHINE_MAX_RAM_BELOW_4G, "size",
> > > > >>+ pc_machine_get_max_ram_below_4g,
> > > > >>+ pc_machine_set_max_ram_below_4g,
> > > > >>+ NULL, NULL, NULL);
> > Maybe you can add here a sane default and avoid comparison with 0
> > any time you use it.
> +1
>
> > If you think you need value per machine type, you can add it to
> > compat props. I don't see how is related, so you may not want to do so.
> Using compat_props would be great however does compat_props work for machine
> type itself already?
Now that you are mentioning it, I was hoping that compat_props are converted
into QemuOpts or something and then mapped into machine properties.
I'll look into it.
>
> >
> > > > >> }
> > > > >> static void pc_machine_class_init(ObjectClass *oc, void *data)
> > > > >>diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > > > >>index 40f6eaf..25f4727 100644
> > > > >>--- a/hw/i386/pc_piix.c
> > > > >>+++ b/hw/i386/pc_piix.c
> > > > >>@@ -98,6 +98,13 @@ static void pc_init1(MachineState *machine,
> > > > >> DeviceState *icc_bridge;
> > > > >> FWCfgState *fw_cfg = NULL;
> > > > >> PcGuestInfo *guest_info;
> > > > >>+ Object *mo = qdev_get_machine();
> > > > >>+ PCMachineState *pcms = PC_MACHINE(mo);
> > > > >>+ ram_addr_t lowmem = 0xe0000000;
> > > > >>+
> > > > >>+ if (pcms && pcms->max_ram_below_4g) {
> > From my QOM understanding, max_ram_below_4g is a private field,
> > so it not should be used directly.
> > You can use QOMs object_property_get or add a pc_machine wrapper
> > for getting/setting the field.
> pc_init1() is sort of private function of PCMachine, so there is no much
> point to use verbose getters/setters internally unless there is checks behind
> setter.
I was just being QOM's advocate :). That being said, I'll not argue here,
as it is not a major issue.
Thanks,
Marcel
>
> >
> > > > >Is pcms ever NULL? If yes why?
> > > >
> > > > Not that I know of. I would be happy to convert this to an
> > > > assert(pcms).
> > >
> > > In fact, PC_MACHINE already includes an assert doesn't it?
> > > So no need to check it everywhere.
> >
> > +1. No need for assert here. Is already done by OBJECT_CHECK.
> >
> > Hope I helped,
> > Marcel
> >
> > >
> > > > >>+ lowmem = pcms->max_ram_below_4g;
> > > > >>+ }
> > > > >> /* Check whether RAM fits below 4G (leaving 1/2 GByte for IO
> > > > >> memory).
> > > > >> * If it doesn't, we need to split it in chunks below and above
> > > > >> 4G.
> > > > >>@@ -106,8 +113,10 @@ static void pc_init1(MachineState *machine,
> > > > >> * For old machine types, use whatever split we used
> > > > >> historically to avoid
> > > > >> * breaking migration.
> > > > >> */
> > > > >>- if (machine->ram_size >= 0xe0000000) {
> > > > >>- ram_addr_t lowmem = gigabyte_align ? 0xc0000000 : 0xe0000000;
> > > > >>+ if (machine->ram_size >= lowmem) {
> > > > >>+ if (!(pcms && pcms->max_ram_below_4g) && gigabyte_align) {
> > > > >>+ lowmem = 0xc0000000;
> > > > >>+ }
> > > > >> above_4g_mem_size = machine->ram_size - lowmem;
> > > > >> below_4g_mem_size = lowmem;
> > > > >> } else {
> > > > >
> > > > >So why do we need gigabyte_align anymore?
> > > >
> > > > Because of qemu 2.0 and the user is not required to specify this option.
> > > >
> > > > >Can't we set property to 0xc0000000 by default, and
> > > > >override for old machine types?
> > > >
> > > > There is a strange compatibility part here. Since this code includes
> > > > ram_size (see:
> > > >
> > > > http://lists.gnu.org/archive/html/qemu-devel/2014-02/msg05146.html
> > > >
> > > > ) and xen has a different default.
> > > >
> > >
> > > So instead of default 0, it would be preferable to set the default to the
> > > actual value, and let user override it.
> > >
> > > Or if that's too hard, set max_ram_below_4g instead of setting
> > > gigabyte_align. gigabyte_align switches everywhere is messy
> > > enough, adding max_ram_below_4g into mix is just too messy.
> > >
> > >
> > >
> > > > >Also, a value that isn't a multiple of 1G will lead to bad
> > > > >performance for large machines which do have above_4g_mem_size.
> > > > >Let's detect and print a warning.
> > > >
> > > > Will Do.
> > > >
> > > > -Don Slutz
> > > >
> > > > >
> > > > >
> > > > >>@@ -122,7 +131,7 @@ static void pc_init1(MachineState *machine,
> > > > >> }
> > > > >> icc_bridge = qdev_create(NULL, TYPE_ICC_BRIDGE);
> > > > >>- object_property_add_child(qdev_get_machine(), "icc-bridge",
> > > > >>+ object_property_add_child(mo, "icc-bridge",
> > > > >> OBJECT(icc_bridge), NULL);
> > > > >> pc_cpus_init(machine->cpu_model, icc_bridge);
> > > > >>diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> > > > >>index e28ce40..155cdf1 100644
> > > > >>--- a/hw/i386/pc_q35.c
> > > > >>+++ b/hw/i386/pc_q35.c
> > > > >>@@ -85,6 +85,13 @@ static void pc_q35_init(MachineState *machine)
> > > > >> PCIDevice *ahci;
> > > > >> DeviceState *icc_bridge;
> > > > >> PcGuestInfo *guest_info;
> > > > >>+ Object *mo = qdev_get_machine();
> > > > >>+ PCMachineState *pcms = PC_MACHINE(mo);
> > > > >>+ ram_addr_t lowmem = 0xb0000000;
> > > > >>+
> > > > >>+ if (pcms && pcms->max_ram_below_4g) {
> > > > >>+ lowmem = pcms->max_ram_below_4g;
> > > > >>+ }
> > > > >> /* Check whether RAM fits below 4G (leaving 1/2 GByte for IO
> > > > >> memory
> > > > >> * and 256 Mbytes for PCI Express Enhanced Configuration Access
> > > > >> Mapping
> > > > >>@@ -95,8 +102,10 @@ static void pc_q35_init(MachineState *machine)
> > > > >> * For old machine types, use whatever split we used
> > > > >> historically to avoid
> > > > >> * breaking migration.
> > > > >> */
> > > > >>- if (machine->ram_size >= 0xb0000000) {
> > > > >>- ram_addr_t lowmem = gigabyte_align ? 0x80000000 : 0xb0000000;
> > > > >>+ if (machine->ram_size >= lowmem) {
> > > > >>+ if (!(pcms && pcms->max_ram_below_4g) && gigabyte_align) {
> > > > >>+ lowmem = 0x800000000;
> > > > >>+ }
> > > > >> above_4g_mem_size = machine->ram_size - lowmem;
> > > > >> below_4g_mem_size = lowmem;
> > > > >> } else {
> > > > >>@@ -111,7 +120,7 @@ static void pc_q35_init(MachineState *machine)
> > > > >> }
> > > > >> icc_bridge = qdev_create(NULL, TYPE_ICC_BRIDGE);
> > > > >>- object_property_add_child(qdev_get_machine(), "icc-bridge",
> > > > >>+ object_property_add_child(mo, "icc-bridge",
> > > > >> OBJECT(icc_bridge), NULL);
> > > > >> pc_cpus_init(machine->cpu_model, icc_bridge);
> > > > >>diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> > > > >>index 19530bd..2d8b562 100644
> > > > >>--- a/include/hw/i386/pc.h
> > > > >>+++ b/include/hw/i386/pc.h
> > > > >>@@ -32,10 +32,13 @@ struct PCMachineState {
> > > > >> MemoryRegion hotplug_memory;
> > > > >> HotplugHandler *acpi_dev;
> > > > >>+
> > > > >>+ uint64_t max_ram_below_4g;
> > > > >> };
> > > > >> #define PC_MACHINE_ACPI_DEVICE_PROP "acpi-device"
> > > > >> #define PC_MACHINE_MEMHP_REGION_SIZE "hotplug-memory-region-size"
> > > > >>+#define PC_MACHINE_MAX_RAM_BELOW_4G "max-ram-below-4g"
> > > > >> /**
> > > > >> * PCMachineClass:
> > > > >>diff --git a/vl.c b/vl.c
> > > > >>index 5e77a27..cffb9c5 100644
> > > > >>--- a/vl.c
> > > > >>+++ b/vl.c
> > > > >>@@ -382,6 +382,10 @@ static QemuOptsList qemu_machine_opts = {
> > > > >> .name = "kvm-type",
> > > > >> .type = QEMU_OPT_STRING,
> > > > >> .help = "Specifies the KVM virtualization mode (HV,
> > > > >> PR)",
> > > > >>+ },{
> > > > >>+ .name = PC_MACHINE_MAX_RAM_BELOW_4G,
> > > > >>+ .type = QEMU_OPT_SIZE,
> > > > >>+ .help = "maximum ram below the 4G boundary (32bit
> > > > >>boundary)",
> > > > >> },
> > > > >> { /* End of list */ }
> > > > >> },
> > > > >>--
> > > > >>1.8.4
> > >
> >
> >
> >
>
>
