On May 9, 2013, at 6:50 AM, satish kondapalli <[email protected]> wrote:
> Hi, > > I have DellR720 server with 16GB of physical Memory. I am testing the option > ROM driver on this server and my driver is executed successfully. But while > booting Linux from hard disk it failed with the following error message on > screen > "can not allocate memory Failed to allocate scratch mem!". > > If i remove my card from server its booted fine. > > Here is my question: > 1) In UEFI, is there any memory allocation size restriction?(In my driver i > allocated EfiBootServicesData memory.) > 2) is it possible to allocate 4GB of pcie DMA capable memory? In my case it > failed for 64MB. The only legal way to allocate a DMA buffer is to use EFI_PCI_IO_PROTOCOL.AllocateBuffer() and then call EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL.Map() with an Operation like EfiPciOperationBusMasterCommonBuffer64. > 3) if i want a 4GB of PCIe DMA capable memory how to allocate? > 13.4 EFI PCI I/O Protocol - EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL.Map() Bus master operations that require both read and write access or require multiple host device interactions within the same mapped region must use EfiPciOperation- BusMasterCommonBuffer or EfiPciOperationBusMasterCommonBuffer64. However, only memory allocated via the AllocateBuffer() interface can be mapped for this type of operation. In all mapping requests the resulting NumberOfBytes actually mapped may be less than the requested amount. In this case, the DMA operation will have to be broken up into smaller chunks. The Map() function will map as much of the DMA operation as it can at one time. The caller may have to loop on Map() and Unmap() in order to complete a large DMA transfer. Note: If you map as EfiPciOperationBusMasterCommonBuffer or EfiPciOperationBusMasterCommonBuffer64 you don't need to Map() and Unmap() on each DMA transfer. Thanks, Andrew Fish PS DMA coherency is for the most part handled in hardware on a PC so not following the rules may appear to work. But if you port that driver to ARM it will fail horribly. Not to mention a massively parallel high end X64 system could fail too if you don't follow the rules. PPS Don't assume that the address of the DMA buffer is the same from the CPU and PCI perspective. The PCI card needs to use DeviceAddress, and it does not have to be the same as the HostAddress. The EFI DMA flows our outlined in13.2 PCI Root Bridge I/O Protocol: DMA Bus Master Read Operation • Call Map() for EfiPciOperationBusMasterRead or EfiPciOperationBusMasterRead64. • Program the DMA Bus Master with the DeviceAddress returned by Map(). • Start the DMA Bus Master. • Wait for DMA Bus Master to complete the read operation. • Call Unmap(). DMA Bus Master Write Operation • Call Map() for EfiPciOperationBusMasterWrite or EfiPciOperationBusMasterRead64. • Program the DMA Bus Master with the DeviceAddress returned by Map(). • Start the DMA Bus Master. • Wait for DMA Bus Master to complete the write operation. • Perform a PCI controller specific read transaction to flush all PCI write buffers (See PCI Specification Section 3.2.5.2) . • Call Flush(). • Call Unmap(). DMA Bus Master Common Buffer Operation • Call AllocateBuffer() to allocate a common buffer. • Call Map() for EfiPciOperationBusMasterCommonBuffer or EfiPciOperationBusMasterCommonBuffer64. • Program the DMA Bus Master with the DeviceAddress returned by Map(). • The common buffer can now be accessed equally by the processor and the DMA bus master. • Call Unmap(). • Call FreeBuffer(). > Thanks > Sateesh > > ------------------------------------------------------------------------------ > Learn Graph Databases - Download FREE O'Reilly Book > "Graph Databases" is the definitive new guide to graph databases and > their applications. This 200-page book is written by three acclaimed > leaders in the field. The early access version is available now. > Download your free book today! > http://p.sf.net/sfu/neotech_d2d_may_______________________________________________ > edk2-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/edk2-devel ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. This 200-page book is written by three acclaimed leaders in the field. The early access version is available now. Download your free book today! http://p.sf.net/sfu/neotech_d2d_may _______________________________________________ edk2-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/edk2-devel
