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Re: [Qemu-ppc] [RFC PATCH v1 2/3] spapr: Remove alignment gap b/n RAM an
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [RFC PATCH v1 2/3] spapr: Remove alignment gap b/n RAM and hotplug regions |
Date: |
Fri, 3 Jun 2016 17:09:08 +1000 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Fri, Jun 03, 2016 at 11:19:43AM +0530, Bharata B Rao wrote:
> Let the alignment b/n RAM and memory hotplug region be equal to
> LMB size (256MB) so that there is no gap b/n RAM and hotplug region.
> This new alignment is true for only pseries-2.7 onwards and the older
> machine types continue to have the earlier 1GB alignment.
>
> Suggested-by: David Gibson <address@hidden>
> Signed-off-by: Bharata B Rao <address@hidden>
Code looks fine, but the commit message needs to explain the rationale
for this (IIUC it's essentially due to a guest bug processing the dt
information describing the gap).
> ---
> hw/ppc/spapr.c | 11 ++++++++++-
> include/hw/ppc/spapr.h | 5 ++---
> 2 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 30b9731..623c35f 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1825,7 +1825,7 @@ static void ppc_spapr_init(MachineState *machine)
> }
>
> spapr->hotplug_memory.base = ROUND_UP(machine->ram_size,
> - SPAPR_HOTPLUG_MEM_ALIGN);
> + smc->hotplug_alignment);
> memory_region_init(&spapr->hotplug_memory.mr, OBJECT(spapr),
> "hotplug-memory", hotplug_mem_size);
> memory_region_add_subregion(sysmem, spapr->hotplug_memory.base,
> @@ -2294,6 +2294,7 @@ static void spapr_machine_class_init(ObjectClass *oc,
> void *data)
> mc->cpu_index_to_socket_id = spapr_cpu_index_to_socket_id;
>
> smc->dr_lmb_enabled = true;
> + smc->hotplug_alignment = SPAPR_MEMORY_BLOCK_SIZE;
> fwc->get_dev_path = spapr_get_fw_dev_path;
> nc->nmi_monitor_handler = spapr_nmi;
> }
> @@ -2369,8 +2370,16 @@ static void
> spapr_machine_2_6_instance_options(MachineState *machine)
>
> static void spapr_machine_2_6_class_options(MachineClass *mc)
> {
> + sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> +
> spapr_machine_2_7_class_options(mc);
> SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_6);
> +
> + /*
> + * 2.6 and older types supported 1GB alignment gap b/n RAM
> + * and hotplug memory region.
> + */
> + smc->hotplug_alignment = G_BYTE;
> }
>
> DEFINE_SPAPR_MACHINE(2_6, "2.6", false);
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 971df3d..b2aeb15 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -37,6 +37,8 @@ struct sPAPRMachineClass {
> /*< public >*/
> bool dr_lmb_enabled; /* enable dynamic-reconfig/hotplug of LMBs */
> bool use_ohci_by_default; /* use USB-OHCI instead of XHCI */
> + hwaddr hotplug_alignment; /* controls the alignment b/n RAM and hotplug
> + regions */
> };
>
> /**
> @@ -610,9 +612,6 @@ int spapr_rng_populate_dt(void *fdt);
> */
> #define SPAPR_MAX_RAM_SLOTS 32
>
> -/* 1GB alignment for hotplug memory region */
> -#define SPAPR_HOTPLUG_MEM_ALIGN (1ULL << 30)
> -
> /*
> * Number of 32 bit words in each LMB list entry in ibm,dynamic-memory
> * property under ibm,dynamic-reconfiguration-memory node.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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