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Old 05-19-2019, 01:30 AM   #1
Mylavarapu Manikanta
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Question memory mapping of memory mapped pci devices


Memory mapped pci device's internal memory will be mapped in RAM.
But where will it be mapped, what I mean to say is,in standard x86 architecture from 0 to 896MB is used for os booting & legacy devices dma mapping. From 896MB to the end of RAM is used for user space processes and kernel stack.

So my doubt is on top of the RAM certain region of memory is reserved for memory mapped pci devices?
(or)
where this memory mapped pci device will be mapped into RAM?

Last edited by Mylavarapu Manikanta; 05-19-2019 at 01:33 AM. Reason: Title mistake
 
Old 05-19-2019, 01:42 AM   #2
berndbausch
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I found an answer at https://stackoverflow.com/questions/...ap-of-a-device. My always-on server has no PCI, but it does have a memory map:
Code:
$ cat /proc/iomem
00200000-041fffff : System RAM
  00208000-00b34bab : Kernel code
  00b6e000-00e775fb : Kernel data
05000000-05ffffff : System RAM
06000000-0e3fffff : Video RAM
0e400000-3cefffff : System RAM
d00c0000-d00c0100 : Mali_GP
d00c1000-d00c1200 : Mali_L2
d00c2000-d00c2100 : Mali_PMU
d00c3000-d00c3100 : Mali_GP_MMU
d00c4000-d00c4100 : Mali_PP0_MMU
d00c5000-d00c5100 : Mali_PP1_MMU
d00c8000-d00c9100 : Mali_PP0
d00ca000-d00cb100 : Mali_PP1
d00d0000-d00d0200 : Mali_L2
d00d2000-d00d2100 : Mali_DMA
d00d3000-d00d3100 : Mali_Broadcast
d00d4000-d00d4100 : Mali_DLBU
d00d5000-d00d5100 : Mali_PP_MMU_Broadcast
d00d6000-d00d7100 : Mali_PP_Broadcast
It looks like device memory is mapped at the end of the physical address space, which is not really surprising.

Last edited by berndbausch; 05-19-2019 at 01:43 AM.
 
  


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