what is ANDROID_PMEM?

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Allen Curtis

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Apr 28, 2011, 2:23:00 PM4/28/11
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Hello,

What is the difference between ANDROID_PMEM and the standard Linux protected memory functions?

For instance, there is currently a conflict between
drivers/char/mem.c AND
drivers/misc/pmem.c

They both have implementations of phys_mem_access_prot() and other routines

The sample Android kernel configurations have not provided any insight.

TIA


Jon Pry

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Apr 28, 2011, 2:52:40 PM4/28/11
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Pmem is a terrible contraption for allocating contiguous regions of physical memory. In essence its like putting holes in the available memory. This is required on many socs that have functional units using main memory. For example a framebuffer might require several megabytes of sdram to not be used by the kernel for anything except framebuffer.

I believe the phys_mem_access_prot() and other multiply defined functions are there because in other kernel versions those functions did not exist or were removed from arch/arm.

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