Re: [PATCH 2/2] arm/virt/acpi: remove _ADR from devices identified by _HID

[Guoheyi <guoheyi@huawei.com>]

在 2020/1/13 23:26, Andrew Jones 写道:
> On Mon, Jan 13, 2020 at 09:57:55PM +0800, Guoheyi wrote:
>> 在 2020/1/13 20:08, Igor Mammedov 写道:
>>> On Thu, 19 Dec 2019 14:47:59 +0800
>>> Heyi Guo <guoheyi@huawei.com> wrote:
>>>
>>>> According to ACPI spec, _ADR should be used for device which is on a
>>>> bus that has a standard enumeration algorithm. It does not make sense
>>>> to have a _ADR object for devices which already have _HID and will be
>>>> enumerated by OSPM.
>>>>
>>>> Signed-off-by: Heyi Guo <guoheyi@huawei.com>
>>> Are you sure it's does not make sense?
>>> Have you checked commit f264d51d8, that added _ADR?
>> I searched in SPCR spec and ACPI spec, but didn't find such requirement for
>> serial port device description.
>>
>> Hi Andrew,
>>
>> Could you help to explain the reason?
> tl;dr: It was a mistake and I agree with removing _ADR from SPCR.
>
> The long version is that ACPI support for ARM took a long time to get
> merged upstream. In the meantime Linaro and Red Hat had ACPI support
> in their downstream trees. The initial, never upstreamed implementation
> of Linux SPCR support used _ADR to find the console UART (probably
> because some vendor hacked their ACPI tables that way). I made the
> mistake of using the out-of-tree Linux kernel code as my "specification".
>
> Upstream kernels never had this problem and I don't think we need to
> worry about any of those downstream kernels which did. They'd be five
> years old by now anyway.
>
> Thanks,
> drew

Thanks for your confirmation, Andrew.

Hi Igor,

On arm64 physical machine, we didn't have _ADR for SPCR serial port 
device attached to system bus either, and we never saw any problem.

Thanks,

Heyi

>> Thanks,
>>
>> Heyi
>>
>>
>>
>>>> ---
>>>> Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
>>>> Cc: Peter Maydell <peter.maydell@linaro.org>
>>>> Cc: "Michael S. Tsirkin" <mst@redhat.com>
>>>> Cc: Igor Mammedov <imammedo@redhat.com>
>>>> Cc: qemu-arm@nongnu.org
>>>> Cc: qemu-devel@nongnu.org
>>>> ---
>>>>    hw/arm/virt-acpi-build.c          |   8 --------
>>>>    tests/data/acpi/virt/DSDT         | Bin 18449 -> 18426 bytes
>>>>    tests/data/acpi/virt/DSDT.memhp   | Bin 19786 -> 19763 bytes
>>>>    tests/data/acpi/virt/DSDT.numamem | Bin 18449 -> 18426 bytes
>>>>    4 files changed, 8 deletions(-)
>>>>
>>>> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
>>>> index 9f4c7d1889..be752c0ad8 100644
>>>> --- a/hw/arm/virt-acpi-build.c
>>>> +++ b/hw/arm/virt-acpi-build.c
>>>> @@ -78,11 +78,6 @@ static void acpi_dsdt_add_uart(Aml *scope, const MemMapEntry *uart_memmap,
>>>>                                 AML_EXCLUSIVE, &uart_irq, 1));
>>>>        aml_append(dev, aml_name_decl("_CRS", crs));
>>>> -    /* The _ADR entry is used to link this device to the UART described
>>>> -     * in the SPCR table, i.e. SPCR.base_address.address == _ADR.
>>>> -     */
>>>> -    aml_append(dev, aml_name_decl("_ADR", aml_int(uart_memmap->base)));
>>>> -
>>>>        aml_append(scope, dev);
>>>>    }
>>>> @@ -170,7 +165,6 @@ static void acpi_dsdt_add_pci(Aml *scope, const MemMapEntry *memmap,
>>>>        aml_append(dev, aml_name_decl("_CID", aml_string("PNP0A03")));
>>>>        aml_append(dev, aml_name_decl("_SEG", aml_int(0)));
>>>>        aml_append(dev, aml_name_decl("_BBN", aml_int(0)));
>>>> -    aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
>>>>        aml_append(dev, aml_name_decl("_UID", aml_string("PCI0")));
>>>>        aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
>>>>        aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
>>>> @@ -334,7 +328,6 @@ static void acpi_dsdt_add_gpio(Aml *scope, const MemMapEntry *gpio_memmap,
>>>>    {
>>>>        Aml *dev = aml_device("GPO0");
>>>>        aml_append(dev, aml_name_decl("_HID", aml_string("ARMH0061")));
>>>> -    aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
>>>>        aml_append(dev, aml_name_decl("_UID", aml_int(0)));
>>>>        Aml *crs = aml_resource_template();
>>>> @@ -364,7 +357,6 @@ static void acpi_dsdt_add_power_button(Aml *scope)
>>>>    {
>>>>        Aml *dev = aml_device(ACPI_POWER_BUTTON_DEVICE);
>>>>        aml_append(dev, aml_name_decl("_HID", aml_string("PNP0C0C")));
>>>> -    aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
>>>>        aml_append(dev, aml_name_decl("_UID", aml_int(0)));
>>>>        aml_append(scope, dev);
>>>>    }
>>>> diff --git a/tests/data/acpi/virt/DSDT b/tests/data/acpi/virt/DSDT
>>>> index b5895cb22446860a0b9be3d32ec856feb388be4c..a759ff739a071d5fbf50519a6aea296e5e0f1e0c 100644
>>>> GIT binary patch
>>>> delta 72
>>>> zcmbO@f$>*ABbQ6COUN&G1_q{66S<_BT5Bh&t1wzk^tIeLL4lL8ZSqD=gU!!5x$Pt+
>>>> c1HyxxIO07#U3dfh0t}oDoEbRcLp@y>07w882mk;8
>>>>
>>>> delta 94
>>>> zcmey>&p2@cBbQ6CONgKc0|V26iCof5J#`b+RhV2^Ci+-%al|{i1o1F1FmP^cRp4ao
>>>> tnY@hCfEg&X`7$S;oxFTNc#soEyoaX?Z-8HbfwO@#16Tu)4E1zj005fm7mWY_
>>>>
>>>> diff --git a/tests/data/acpi/virt/DSDT.memhp b/tests/data/acpi/virt/DSDT.memhp
>>>> index 69ad844f65d047973a3e55198beecd45a35b8fce..6e5cc61977e4cd24f765fec0693f75a528c144c1 100644
>>>> GIT binary patch
>>>> delta 72
>>>> zcmX>#i*fTTMlP3Nmk?uL1_q|eiCof5eHSLGt1wzk^tIeLL4lL8ZSqD=gU!!5U7RH)
>>>> c1HyxxIO07#U3dfh0t}oDoEbRcLp@y>03)CjmjD0&
>>>>
>>>> delta 94
>>>> zcmdlyi}BPfMlP3Nmk=*s1_q}3iCof5t(PXMt1!8;O!Tqj;)r*23F2X3VBp-?s=&$E
>>>> tGkF=O0W(l&^JPwVXL<R6@E|9Scn?n(-T=P<17`zg2CxPo8S3f6006qZ7#siq
>>>>
>>>> diff --git a/tests/data/acpi/virt/DSDT.numamem b/tests/data/acpi/virt/DSDT.numamem
>>>> index b5895cb22446860a0b9be3d32ec856feb388be4c..a759ff739a071d5fbf50519a6aea296e5e0f1e0c 100644
>>>> GIT binary patch
>>>> delta 72
>>>> zcmbO@f$>*ABbQ6COUN&G1_q{66S<_BT5Bh&t1wzk^tIeLL4lL8ZSqD=gU!!5x$Pt+
>>>> c1HyxxIO07#U3dfh0t}oDoEbRcLp@y>07w882mk;8
>>>>
>>>> delta 94
>>>> zcmey>&p2@cBbQ6CONgKc0|V26iCof5J#`b+RhV2^Ci+-%al|{i1o1F1FmP^cRp4ao
>>>> tnY@hCfEg&X`7$S;oxFTNc#soEyoaX?Z-8HbfwO@#16Tu)4E1zj005fm7mWY_
>>>>
>>> .
>>
>
> .