From: "Gabriel L. Somlo" <somlo@cmu.edu>
To: Igor Mammedov <imammedo@redhat.com>
Cc: peter.maydell@linaro.org, ehabkost@redhat.com, mst@redhat.com,
matt@codeblueprint.co.uk, stefanha@gmail.com,
ard.biesheuvel@linaro.org, qemu-devel@nongnu.org,
leif.lindholm@linaro.org, luto@amacapital.net,
qemu-arm@nongnu.org, kraxel@redhat.com, pbonzini@redhat.com,
lersek@redhat.com, rth@twiddle.net
Subject: Re: [Qemu-devel] [PATCH v8 3/5] acpi: pc: add fw_cfg device node to dsdt
Date: Fri, 19 Feb 2016 11:59:02 -0500 [thread overview]
Message-ID: <20160219165902.GY16357@HEDWIG.INI.CMU.EDU> (raw)
In-Reply-To: <20160219144953.03aff7eb@nial.brq.redhat.com>
On Fri, Feb 19, 2016 at 02:49:53PM +0100, Igor Mammedov wrote:
> On Thu, 11 Feb 2016 17:06:03 -0500
> "Gabriel L. Somlo" <somlo@cmu.edu> wrote:
>
> > Add a fw_cfg device node to the ACPI DSDT. While the guest-side
> > firmware can't utilize this information (since it has to access
> > the hard-coded fw_cfg device to extract ACPI tables to begin with),
> > having fw_cfg listed in ACPI will help the guest kernel keep a more
> > accurate inventory of in-use IO port regions.
> >
> > Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
> > Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> > Reviewed-by: Marc Marí <markmb@redhat.com>
> > ---
> > hw/i386/acpi-build.c | 29 +++++++++++++++++++++++++++++
> > 1 file changed, 29 insertions(+)
> >
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index 4554eb8..4762fd2 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -2190,6 +2190,35 @@ build_dsdt(GArray *table_data, GArray *linker,
> > aml_append(scope, aml_name_decl("_S5", pkg));
> > aml_append(dsdt, scope);
> >
> > + /* create fw_cfg node, unconditionally */
> > + {
> > + /* when using port i/o, the 8-bit data register *always* overlaps
> > + * with half of the 16-bit control register. Hence, the total size
> > + * of the i/o region used is FW_CFG_CTL_SIZE; when using DMA, the
> > + * DMA control register is located at FW_CFG_DMA_IO_BASE + 4 */
> > + uint8_t io_size = object_property_get_bool(OBJECT(pcms->fw_cfg),
> > + "dma_enabled", NULL) ?
> > + ROUND_UP(FW_CFG_CTL_SIZE, 4) + sizeof(dma_addr_t) :
> > + FW_CFG_CTL_SIZE;
> > +
> > + scope = aml_scope("\\_SB");
> > + dev = aml_device("FWCF");
> > +
> > + aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
> From my tests with different Windows versions, it doesn't prevent
> WS2003 and WS2008 from showing a prompt for unknown device that asks for a driver.
I installed windows 2008 server r2 64bit, on both pc and q35 machines,
and still only saw the "unknown device" in the Device Manager after
forcing _STA to 0xF (instead of 0xB).
> One however could shut it up by allowing OS look for a driver
> which is not found and then tell not to ask for it anymore.
It's entirely possible that "after a while" something would pop up and
ask for a driver anyway. I did try to "humor it" by allowing it to
search for a driver, and it failed, and the device was still showing
up as unknown (remember, this is with _STA set to 0xF, which I did
only to force it to show up :)
I never waited around long enough for it to prompt me, so that may be
the difference between our tests...
>
> So existing users will have to perform this action once
> they have migrated to newer QEMU regardless of machine version.
>
> > +
> > + /* device present, functioning, decoding, not shown in UI */
> > + aml_append(dev, aml_name_decl("_STA", aml_int(0xB)));
> > +
> > + crs = aml_resource_template();
> > + aml_append(crs,
> > + aml_io(AML_DECODE16, FW_CFG_IO_BASE, FW_CFG_IO_BASE, 0x01, io_size)
> > + );
> that creates \_SB.FWCF._CRS
> + Name (_CRS, ResourceTemplate () // _CRS: Current Resource Settings
> + {
> + IO (Decode16,
> + 0x0510, // Range Minimum
> + 0x0510, // Range Maximum
> + 0x01, // Alignment
> + 0x0C, // Length
> + )
> + })
>
> which collides with \_SB.PCI0._CRS
> WordIO (ResourceProducer, MinFixed, MaxFixed, PosDecode, EntireRange,
> 0x0000, // Granularity
> 0x0000, // Range Minimum
> 0x0CF7, // Range Maximum
> 0x0000, // Translation Offset
> 0x0CF8,
>
> that shouldn't happen, and solution for this is to put
> FWCF device descriptor in \_SB.PCI0 scope so FWCF would consume
> from PCI0 IO range.
>
> That won't help Windows to notice a conflict, if there is any,
> as there aren't any drivers for QEMU0002 device but at least
> when Windows gets a driver it won't crash due above conflict.
OK, so the difference between "\_SB" and "\_SB.PCI0" is that, with
_STA forced to 0xF, the "resources" tab of the "unknown device" no
longer shows conflicts on the IO range of 510-518.
With that being said, I still hope most people won't ever make it this
far (with _STA set to 0xB). But in case they ever do, yes, placing
FWCF in \_SB.PCI0 should take care of it -- thanks for showing me that!
V9 (coming up soon) should reflect that change.
Thanks much,
--Gabriel
>
> > + aml_append(dev, aml_name_decl("_CRS", crs));
> > +
> > + aml_append(scope, dev);
> > + aml_append(dsdt, scope);
> > + }
> > +
> > if (misc->applesmc_io_base) {
> > scope = aml_scope("\\_SB.PCI0.ISA");
> > dev = aml_device("SMC");
>
next prev parent reply other threads:[~2016-02-19 16:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-11 22:06 [Qemu-devel] [PATCH v8 0/5] add ACPI node for fw_cfg on pc and arm Gabriel L. Somlo
2016-02-11 22:06 ` [Qemu-devel] [PATCH v8 1/5] fw_cfg: expose control register size in fw_cfg.h Gabriel L. Somlo
2016-02-11 22:06 ` [Qemu-devel] [PATCH v8 2/5] pc: fw_cfg: move ioport base constant to pc.h Gabriel L. Somlo
2016-02-11 22:06 ` [Qemu-devel] [PATCH v8 3/5] acpi: pc: add fw_cfg device node to dsdt Gabriel L. Somlo
2016-02-19 13:49 ` Igor Mammedov
2016-02-19 16:59 ` Gabriel L. Somlo [this message]
2016-02-11 22:06 ` [Qemu-devel] [PATCH v8 4/5] acpi: arm: " Gabriel L. Somlo
2016-02-11 22:06 ` [Qemu-devel] [PATCH v8 5/5] fw_cfg: document ACPI device node information Gabriel L. Somlo
2016-02-16 23:49 ` [Qemu-devel] [PATCH v8 0/5] add ACPI node for fw_cfg on pc and arm Gabriel L. Somlo
2016-02-19 7:08 ` Gerd Hoffmann
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