On Thu, 2016-05-19 at 00:12 +0200, Laszlo Ersek wrote: > According to edk2 commit > > "MdeModulePkg/PciBus: do not improperly degrade resource" > > and to the EFI_INCOMPATIBLE_PCI_DEVICE_SUPPORT_PROTOCOL definition in the > Platform Init 1.4a specification, a platform can provide such a protocol > in order to influence the PCI resource allocation performed by the PCI Bus > driver. > > In particular it is possible instruct the PCI Bus driver, with a > "wildcard" hint, to allocate the 64-bit MMIO BARs of a device in 64-bit > address space, regardless of whether the device features an option ROM. > > (By default, the PCI Bus driver considers an option ROM reason enough for > allocating the 64-bit MMIO BARs in 32-bit address space. It cannot know if > BDS will launch a legacy boot option, and under legacy boot, a legacy BIOS > binary from a combined option ROM could be dispatched, and fail to access > MMIO BARs in 64-bit address space.) > > In platform code we can ascertain whether a CSM is present or not. If not, > then legacy BIOS binaries in option ROMs can't be dispatched, hence the > BAR degradation is detrimental, and we should prevent it. This is expected > to conserve the 32-bit address space for 32-bit MMIO BARs. > > The driver added in this patch could be simplified based on the following > facts: > > - In the Ia32 build, the 64-bit MMIO aperture is always zero-size, hence > the driver will exit immediately. Therefore the driver could be omitted > from the Ia32 build. > > - In the Ia32X64 and X64 builds, the driver could be omitted if CSM_ENABLE > was defined (because in that case the degradation would be justified). > On the other hand, if CSM_ENABLE was undefined, then the driver could be > included, and it could provide the hint unconditionally (without looking > for the Legacy BIOS protocol). > > These short-cuts are not taken because they would increase the differences > between the OVMF DSC/FDF files. If we can manage without extreme > complexity, we should use dynamic logic (vs. build time configuration), > plus keep conditional compilation to a minimum. > > Cc: Jordan Justen <jordan.l.jus...@intel.com> > Cc: Ruiyu Ni <ruiyu...@intel.com> > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Laszlo Ersek <ler...@redhat.com>
This (commit 855743f717745) appears not to be working any more. I see NVMe controllers' BARs being assigned above 4GiB where the CSM can't reach them. -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#42596): https://edk2.groups.io/g/devel/message/42596 Mute This Topic: https://groups.io/mt/32122513/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
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