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Re: [Qemu-devel] [PATCH v4 3/7] fw-cfg: expose "file_slots" parameter in
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH v4 3/7] fw-cfg: expose "file_slots" parameter in fw_cfg_init_io_dma() |
Date: |
Tue, 6 Dec 2016 17:46:51 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 |
On 12/06/16 12:49, Igor Mammedov wrote:
> On Thu, 1 Dec 2016 18:06:20 +0100
> Laszlo Ersek <address@hidden> wrote:
>
>> Accordingly, generalize the "file_slots" minimum calculation in
>> fw_cfg_init_io_dma(), and move the constant FW_CFG_FILE_SLOTS_TRAD
>> argument to the callers of fw_cfg_init_io_dma().
> If I get idea correctly you're extending fw_cfg_init_io_dma() and
> setting
> qdev_prop_set_uint32(dev, "file_slots", file_slots);
> manually to keep old fw_cfg_init_io() the same without touching
> xen/sun4u machines.
First, to my knowledge, Xen does not use fw_cfg. The following call
chains depend on (!xen_enabled()):
pc_init1() | pc_q35_init()
if (!xen_enabled()):
pc_memory_init()
bochs_bios_init()
fw_cfg_init_io_dma()
Second, I wanted to keep the fw_cfg_init_io() call sites un-touched. In
this patch, the fw_cfg_init_io() function passes an additional /
internal-only parameter to fw_cfg_init_io_dma(), and the unconditional
qdev_prop_set_uint32() call in fw_cfg_init_io_dma() is replaced with a
conditional one (so that the property can only be lowered, not raised,
by board code).
> That way we would have 2 different ways to set defaults
> per machine type/version rather then the single COMPAT property way.
>
> How about dropping this patch and adding
> SET_MACHINE_COMPAT
> to xen/sun4u machines instead and dropping fw_cfg_init_io() in
> favor of fw_cfg_init_io_dma() along the way.
For the conditional qdev_prop_set_uint32() call, added in this patch, I
used commit e6915b5f3a87 ("fw_cfg: unbreak migration compatibility for
2.4 and earlier machines") as model. According to that model, I couldn't
drop this patch completely, because the new feature -- i.e., DMA in that
patch, and higher fw_cfg file slots in this patch -- depends on both
machine versions and board opt-in.
However, if we agree (according to your feedback on patch v4 2/7) that
we will silently bump the fw_cfg file count for all new machine
versions, without requiring (or permitting) board opt-in / opt-out, then
I agree your above suggestion is consistent with that.
I think I don't have to drop fw_cfg_init_io() actually. But, with the
board opt-in going away, I can drop both the additional "file_slots"
parameter in fw_cfg_init_io_dma(), and the qdev_prop_set_uint32() call
in it (even the unconditional one).
In fact I like this simplicity more, I just wanted to be extra cautious
in the first version of the series that turned file_slots into a property.
... Actually, are sun4u machines versioned? Hm... "hw/sparc64/sun4u.c"
doesn't seem to define versioned machine types. Doesn't that imply that
migration is *completely* unsupported for sun4u? Because, if that's the
case, then I wouldn't even have to add SET_MACHINE_COMPAT().
Thanks!
Laszlo
>
>>
>> Cc: "Gabriel L. Somlo" <address@hidden>
>> Cc: "Michael S. Tsirkin" <address@hidden>
>> Cc: Gerd Hoffmann <address@hidden>
>> Cc: Igor Mammedov <address@hidden>
>> Cc: Paolo Bonzini <address@hidden>
>> Signed-off-by: Laszlo Ersek <address@hidden>
>> ---
>> docs/specs/fw_cfg.txt | 4 ++--
>> include/hw/nvram/fw_cfg.h | 2 +-
>> hw/i386/pc.c | 3 ++-
>> hw/nvram/fw_cfg.c | 13 ++++++-------
>> 4 files changed, 11 insertions(+), 11 deletions(-)
>>
>> diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt
>> index 84e2978706f5..4a6888b511f4 100644
>> --- a/docs/specs/fw_cfg.txt
>> +++ b/docs/specs/fw_cfg.txt
>> @@ -153,12 +153,12 @@ Selector Reg. Range Usage
>> 0x4000 - 0x7fff Generic (0x0000 - 0x3fff, RW, ignored in QEMU v2.4+)
>> 0x8000 - 0xbfff Arch. Specific (0x0000 - 0x3fff, generally RO, possibly RW
>> through the DMA interface in QEMU v2.9+)
>> 0xc000 - 0xffff Arch. Specific (0x0000 - 0x3fff, RW, ignored in v2.4+)
>>
>> -In practice, the number of allowed firmware configuration items is given
>> -by the value (FW_CFG_FILE_FIRST + FW_CFG_FILE_SLOTS_TRAD) (see fw_cfg.h).
>> +In practice, the number of allowed firmware configuration items depends on
>> the
>> +machine type.
> machine type/version
>
>>
>> = Guest-side DMA Interface =
>>
>> If bit 1 of the feature bitmap is set, the DMA interface is present. This
>> does
>> not replace the existing fw_cfg interface, it is an add-on. This interface
>> diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
>> index b980cbaebf43..e9a6b6aa968c 100644
>> --- a/include/hw/nvram/fw_cfg.h
>> +++ b/include/hw/nvram/fw_cfg.h
>> @@ -173,11 +173,11 @@ void fw_cfg_add_file_callback(FWCfgState *s, const
>> char *filename,
>> */
>> void *fw_cfg_modify_file(FWCfgState *s, const char *filename, void *data,
>> size_t len);
>>
>> FWCfgState *fw_cfg_init_io_dma(uint32_t iobase, uint32_t dma_iobase,
>> - AddressSpace *dma_as);
>> + AddressSpace *dma_as, uint32_t file_slots);
>> FWCfgState *fw_cfg_init_io(uint32_t iobase);
>> FWCfgState *fw_cfg_init_mem(hwaddr ctl_addr, hwaddr data_addr);
>> FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr,
>> hwaddr data_addr, uint32_t data_width,
>> hwaddr dma_addr, AddressSpace *dma_as);
>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index a9e64a88e5e7..5d929d8fc887 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -741,11 +741,12 @@ static FWCfgState *bochs_bios_init(AddressSpace *as,
>> PCMachineState *pcms)
>> {
>> FWCfgState *fw_cfg;
>> uint64_t *numa_fw_cfg;
>> int i, j;
>>
>> - fw_cfg = fw_cfg_init_io_dma(FW_CFG_IO_BASE, FW_CFG_IO_BASE + 4, as);
>> + fw_cfg = fw_cfg_init_io_dma(FW_CFG_IO_BASE, FW_CFG_IO_BASE + 4, as,
>> + FW_CFG_FILE_SLOTS_TRAD);
>> fw_cfg_add_i16(fw_cfg, FW_CFG_NB_CPUS, pcms->boot_cpus);
>>
>> /* FW_CFG_MAX_CPUS is a bit confusing/problematic on x86:
>> *
>> * For machine types prior to 1.8, SeaBIOS needs FW_CFG_MAX_CPUS for
>> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
>> index 2e1441c09750..c33c76ab93b1 100644
>> --- a/hw/nvram/fw_cfg.c
>> +++ b/hw/nvram/fw_cfg.c
>> @@ -926,11 +926,11 @@ static void fw_cfg_init1(DeviceState *dev)
>> s->machine_ready.notify = fw_cfg_machine_ready;
>> qemu_add_machine_init_done_notifier(&s->machine_ready);
>> }
>>
>> FWCfgState *fw_cfg_init_io_dma(uint32_t iobase, uint32_t dma_iobase,
>> - AddressSpace *dma_as)
>> + AddressSpace *dma_as, uint32_t file_slots)
>> {
>> DeviceState *dev;
>> FWCfgState *s;
>> uint32_t version = FW_CFG_VERSION;
>> bool dma_requested = dma_iobase && dma_as;
>> @@ -940,15 +940,14 @@ FWCfgState *fw_cfg_init_io_dma(uint32_t iobase,
>> uint32_t dma_iobase,
>> qdev_prop_set_uint32(dev, "dma_iobase", dma_iobase);
>> if (!dma_requested) {
>> qdev_prop_set_bit(dev, "dma_enabled", false);
>> }
>>
>> - /* Once we expose the "file_slots" property to callers of
>> - * fw_cfg_init_io_dma(), the following setting should become
>> conditional on
>> - * the input parameter being lower than the current value of the
>> property.
>> - */
>> - qdev_prop_set_uint32(dev, "file_slots", FW_CFG_FILE_SLOTS_TRAD);
>> + if (file_slots < object_property_get_int(OBJECT(dev), "file_slots",
>> + &error_abort)) {
>> + qdev_prop_set_uint32(dev, "file_slots", file_slots);
>> + }
>>
>> fw_cfg_init1(dev);
>> s = FW_CFG(dev);
>>
>> if (s->dma_enabled) {
>> @@ -964,11 +963,11 @@ FWCfgState *fw_cfg_init_io_dma(uint32_t iobase,
>> uint32_t dma_iobase,
>> return s;
>> }
>>
>> FWCfgState *fw_cfg_init_io(uint32_t iobase)
>> {
>> - return fw_cfg_init_io_dma(iobase, 0, NULL);
>> + return fw_cfg_init_io_dma(iobase, 0, NULL, FW_CFG_FILE_SLOTS_TRAD);
>> }
>>
>> FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr,
>> hwaddr data_addr, uint32_t data_width,
>> hwaddr dma_addr, AddressSpace *dma_as)
>
[Qemu-devel] [PATCH v4 2/7] fw-cfg: turn FW_CFG_FILE_SLOTS into a device property, Laszlo Ersek, 2016/12/01
Re: [Qemu-devel] [PATCH v4 2/7] fw-cfg: turn FW_CFG_FILE_SLOTS into a device property, Igor Mammedov, 2016/12/06