Hi Heyi, On 20 December 2017 at 08:21, Heyi Guo <[email protected]> wrote: > PCIe on some ARM platforms requires address translation, not only for > legacy IO access, but also for 32bit memory BAR access as well. There > will be "Address Translation Unit" or something similar in PCI host > bridges to translation CPU address to PCI address and vice versa. So > we think it may be useful to add address translation support to the > generic PCI host bridge driver. >
I agree. While unusual on a PC, it is quite common on other architectures to have more complex non 1:1 topologies, which currently require a forked PciHostBridgeDxe driver with local changes applied. > This RFC only contains one minor change to the definition of > PciHostBridgeLib, and there certainly will be a lot of other changes > to make it work, including: > > 1. Use CPU address for GCD space add and allocate operations, instead > of PCI address; also IO space will be changed to memory space if > translation exists. > For I/O space, the translation should simply be applied to the I/O range. I don't think it makes sense to use memory space here, given that it is specific to architectures that lack native port I/O. > 2. RootBridgeIoMemRead/Write, RootBridgeIoRead/Write need to get > translation of the corresponding aperture, add the translation to the > input address, and then call CpuIo2 protocol; IO access will also be > converted to memory access if IO translation exists. > Again, why is this necessary? A host bridge that implements a non 1:1 translation for port I/O ranges may be part of a system that has native port I/O, and so the translation should be based on that. > 3. RootBridgeIoConfiguration needs to fill AddrTranslationOffset in > the discriptor. > Indeed. Note that this has been a source of much confusion lately, should we should discuss this carefully before spending time on an implementation. > If it makes sense, then I'll continue to prepare the formal patch. > > Any comments? > > Thanks, > > Gary (Heyi Guo) > > Cc: Star Zeng <[email protected]> > Cc: Eric Dong <[email protected]> > Cc: Ruiyu Ni <[email protected]> > Cc: Ard Biesheuvel <[email protected]> > Cc: Jason Zhang <[email protected]> > > --- > MdeModulePkg/Include/Library/PciHostBridgeLib.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/MdeModulePkg/Include/Library/PciHostBridgeLib.h > b/MdeModulePkg/Include/Library/PciHostBridgeLib.h > index d42e9ec..b9e8c0f 100644 > --- a/MdeModulePkg/Include/Library/PciHostBridgeLib.h > +++ b/MdeModulePkg/Include/Library/PciHostBridgeLib.h > @@ -22,6 +22,7 @@ > typedef struct { > UINT64 Base; > UINT64 Limit; > + UINT64 Translation; > } PCI_ROOT_BRIDGE_APERTURE; > > typedef struct { > -- > 2.7.4 > _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
