Haw-Yuan Yang
2007-Mar-16 23:27 UTC
[Xen-devel] Physical address mapping to user space in dom0 problem
I have a PCI device which can perform bus master DMA. I developed a PCI device driver which can allocate DMA buffer and provide mmap operation to map the I/O and DMA buffer to user space. The PCI device driver works well under Linux 2.6.20. However it brokes under XEN 3.0.4. It appears that mmap map to the wrong memory. remap_pfn_range in mmap function return no error when it is used to map both I/O and DMA buffer. If I use io_remap_pfn_range instead of remap_pfn_range, I/O mapping works but DMA buffer mapping return -1. Is this a known problem for XEN 3.0.4 and will be fixed later? Is there any alternative way to map the DMA address to user space in XEN dom0? Thanks in advance, hyang _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2007-Mar-16 23:31 UTC
Re: [Xen-devel] Physical address mapping to user space in dom0 problem
On 16/3/07 23:27, "Haw-Yuan Yang" <hawyuan@gmail.com> wrote:> Is there any alternative way to map the DMA address to user space in XEN dom0?Mmap via /dev/mem will work. It uses direct_remap_pfn_range(). -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Haw-Yuan Yang
2007-Mar-17 00:36 UTC
Re: [Xen-devel] Physical address mapping to user space in dom0 problem
It still not working. Here is what I did: In driver I have an IOCTL option IO_DMA_ALLOC to allocate the DMA buffer by using pci_alloc_consistent() and return the allocated physical address to user space. In user space testing program: 1. Call IOCTL IO_DMA_ALLOC to allocate a 64Kbyte DMA buffer. The physical address of the allocated buffer is 0x03bb0000. 2. Open /dev/mem and call mmap(0,64*1024,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0x03bb0000) ; the return of mmap is -1. On 3/16/07, Keir Fraser <keir@xensource.com> wrote:> > > > > On 16/3/07 23:27, "Haw-Yuan Yang" <hawyuan@gmail.com> wrote: > > Is there any alternative way to map the DMA address to user space in XEN > dom0? > > > Mmap via /dev/mem will work. It uses direct_remap_pfn_range(). > > -- Keir >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2007-Mar-17 07:57 UTC
Re: [Xen-devel] Physical address mapping to user space in dom0 problem
You want to mmap() the dma_handle, not the CPU pointer. -- Keir On 17/3/07 00:36, "Haw-Yuan Yang" <hawyuan@gmail.com> wrote:> In driver I have an IOCTL option IO_DMA_ALLOC to allocate the DMA buffer by > using pci_alloc_consistent() and return the allocated physical address to user > space. > > In user space testing program: > > 1. Call IOCTL IO_DMA_ALLOC to allocate a 64Kbyte DMA buffer. The physical > address of the allocated buffer is 0x03bb0000. > 2. Open /dev/mem and call > mmap(0,64*1024,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0x03bb0000) ; > > the return of mmap is -1._______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Haw-Yuan Yang
2007-Mar-17 21:52 UTC
Re: [Xen-devel] Physical address mapping to user space in dom0 problem
I knew that pci_alloc_consistent() will return both kernel virtual address and physical address. If I pass the physical address (dma_handler) to mmap, it return -1. However if I pass the kernel virtual address to mmap, I got a pointer point to the worng memory. hyang On 3/17/07, Keir Fraser <keir@xensource.com> wrote:> > You want to mmap() the dma_handle, not the CPU pointer. > > -- Keir > > On 17/3/07 00:36, "Haw-Yuan Yang" <hawyuan@gmail.com> wrote: > > In driver I have an IOCTL option IO_DMA_ALLOC to allocate the DMA buffer > by using pci_alloc_consistent() and return the allocated physical address to > user space. > > In user space testing program: > > 1. Call IOCTL IO_DMA_ALLOC to allocate a 64Kbyte DMA buffer. The physical > address of the allocated buffer is 0x03bb0000. > 2. Open /dev/mem and call > mmap(0,64*1024,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0x03bb0000) ; > > the return of mmap is -1. > > >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2007-Mar-18 08:59 UTC
Re: [Xen-devel] Physical address mapping to user space in dom0 problem
On 17/3/07 21:52, "Haw-Yuan Yang" <hawyuan@gmail.com> wrote:> I knew that pci_alloc_consistent() will return both kernel virtual address and > physical address. If I pass the physical address (dma_handler) to mmap, it > return -1. However if I pass the kernel virtual address to mmap, I got a > pointer point to the worng memory.Oh, I see the problem. You can only mmap() MMIO regions using /dev/mem when running on Xen. Could your device (which you already implement ioctl() for) also implement mmap() itself? Then you can simply remap_pfn_range(virt_to_phys(cpu-ptr-returned-by-pci-alloc-consistent)). This would be a neater interface to userspace for your device anyway, imo. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Haw-Yuan Yang
2007-Mar-18 20:11 UTC
Re: [Xen-devel] Physical address mapping to user space in dom0 problem
Thanks, It works.
Here is what I have in the mmap handler:
if the physical address is MMIO
io_remap_pfn_range(MMIO_address)
else
remap_pfn_range(virt_to_phys(cpu-ptr-returned-by-pci-alloc-consistent)
hyang
On 3/18/07, Keir Fraser <keir@xensource.com>
wrote:>
>
>
>
> On 17/3/07 21:52, "Haw-Yuan Yang" <hawyuan@gmail.com>
wrote:
>
> I knew that pci_alloc_consistent() will return both kernel virtual address
> and physical address. If I pass the physical address (dma_handler) to mmap,
> it return -1. However if I pass the kernel virtual address to mmap, I got a
> pointer point to the worng memory.
>
>
> Oh, I see the problem. You can only mmap() MMIO regions using /dev/mem
> when running on Xen. Could your device (which you already implement ioctl()
> for) also implement mmap() itself? Then you can simply
> remap_pfn_range(virt_to_phys(cpu-ptr-returned-by-pci-alloc-consistent)).
> This would be a neater interface to userspace for your device anyway, imo.
>
> -- Keir
>
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Keir Fraser
2007-Mar-18 21:14 UTC
Re: [Xen-devel] Physical address mapping to user space in dom0 problem
On 18/3/07 20:11, "Haw-Yuan Yang" <hawyuan@gmail.com> wrote:> Here is what I have in the mmap handler: > > if the physical address is MMIO > io_remap_pfn_range(MMIO_address) > else > remap_pfn_range(virt_to_phys(cpu-ptr-returned-by-pci-alloc-consistent)Well, perhaps you can simplify your own mmap() handler since you perhaps know that it will only be used to mmap() your pci_alloc_consistent() memory block. Hence you may only need to handle the remap_pfn_range() case. But anyway, you have the idea now. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel