Messages in this thread | | | From | Jesse Barnes <> | Subject | Re: Special handling of sysfs device resource files? | Date | Wed, 12 Apr 2006 10:14:35 -0700 |
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On Tuesday, April 11, 2006 4:59 pm, Ian Romanick wrote: > Ian Romanick wrote: > > I'm in the process of modifying X to be civilized in it's handling > > of PCI devices on Linux. As part of that, I've modified it to map > > the /sys/bus/pci/device/*/resource[0-6] files instead of mucking > > about with /dev/mem. > > > > This seems to mostly work, but I am having one problem. I map the > > region by opening the file with O_RDWR, then mmap with > > (PROT_READ|PROT_WRITE) and MAP_SHARED. In all cases, the open and > > mmap succeed. However, for I/O BARs, the resulting pointer from > > mmap is invalid. Any access to it results in a segfault and GDB > > says it's "out of range". > > I was a little mistaken about this. The BAR that causes the problem > is not I/O. It *is* memory. > > 01:00.0 VGA compatible controller: Matrox Graphics, Inc. G400/G450 > (rev 03) (prog-if 00 [VGA]) > Subsystem: Matrox Graphics, Inc. Millennium G400 16Mb SGRAM > Flags: bus master, medium devsel, latency 64, IRQ 11 > Memory at cc000000 (32-bit, prefetchable) [size=32M] > Memory at cfefc000 (32-bit, non-prefetchable) [size=16K] > Memory at cf000000 (32-bit, non-prefetchable) [size=8M] > Expansion ROM at cfee0000 [disabled] [size=64K] > > When I open and mmap resource0 (the framebuffer) I get 0x2b9aa48ea000. > When I open and mmap resource1 (the card's registers) I get > 0x2b9aa68ea000. I can access the resource0 pointer all day long > without problems. The firs access to the resource1 pointer results in > a segfault.
Hm, that's strange. On my via machine I can access all my VGA resources correctly, but that's not x86-64. Maybe the x86-64 implementation of pci_mmap_page_range is doing the wrong thing for uncacheable, non-WC regions somehow?
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