Re: [PATCH 0/3] ArmPkg ArmVirtPkg: prevent 64-bit MMIO BAR degradation

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 12 September 2016 at 04:57, Laszlo Ersek <lersek@redhat.com> wrote:
> On 09/12/16 12:01, Ard Biesheuvel wrote:
>> On ARM/Linux systems, the PCI layer is usually reconfigured from scratch,
>> given the embedded legacy of ARM systems. However, when booting arm64/Linux
>> in ACPI mode, such reconfiguration can be avoided, since ACPI implies UEFI
>> implies firmware (as opposed to DT mode, which could be booted via QEMU's
>> ~10 instruction bootloader)
>>
>> In this case, it is important for the firmware to leave the PCI configuration
>> in a reasonable state, and one of the things that UEFI does by default, and
>> which makes no sense at all on an arm64 system, is to degrade 64-bit MMIO BARs
>> to 32-bit in the presence of a ROM BAR on the same device. (It does makes sense
>> on an Intel system running legacy option ROMs under a CSM)
>>
>> Fortunately, we have a way of influencing this policy without having to hack
>> the generic PCI bus driver: we can install the IncompatiblePciDeviceSupport
>> protocol, and the PCI bus driver will invoke it for each PCI device it
>> configures.
>>
>> Our implementation for ArmPkg is simply the OVMF version with the bits ripped
>> out that care about CSMs and legacy BIOSes
>>
>> Ard Biesheuvel (3):
>>   ArmPkg: add driver to force 64-bit MMIO BARs to be allocated above 4
>>     GB
>>   ArmVirtPkg/FdtPciPcdProducerLib: add discovery of PcdPciMmio64Size
>>   ArmVirtPkg/ArmVirtQemu: add IncompatiblePciDeviceSupportDxe
>>
>>  ArmPkg/Drivers/IncompatiblePciDeviceSupportDxe/IncompatiblePciDeviceSupport.c   | 223 ++++++++++++++++++++
>>  ArmPkg/Drivers/IncompatiblePciDeviceSupportDxe/IncompatiblePciDeviceSupport.inf |  49 +++++
>>  ArmVirtPkg/ArmVirtQemu.dsc                                                      |   5 +
>>  ArmVirtPkg/ArmVirtQemuFvMain.fdf.inc                                            |   1 +
>>  ArmVirtPkg/ArmVirtQemuKernel.dsc                                                |   5 +
>>  ArmVirtPkg/Library/FdtPciPcdProducerLib/FdtPciPcdProducerLib.c                  |  31 +--
>>  ArmVirtPkg/Library/FdtPciPcdProducerLib/FdtPciPcdProducerLib.inf                |   1 +
>>  7 files changed, 302 insertions(+), 13 deletions(-)
>>  create mode 100644 ArmPkg/Drivers/IncompatiblePciDeviceSupportDxe/IncompatiblePciDeviceSupport.c
>>  create mode 100644 ArmPkg/Drivers/IncompatiblePciDeviceSupportDxe/IncompatiblePciDeviceSupport.inf
>>
>
> Formatting / reviewing the first patch with "--find-copies-harder" works
> wonders, so I recommend that flag for similar future posts.
>
> Series
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>

Thanks all, but this series is no longer needed now that the PCI
64-bit MMIO BAR degradation quirk has been made X86-only
So dropping this series.

-- 
Ard.