Re: gaps in process's virtual address space(/proc/pid/maps)

["Mulyadi Santosa" <mulyadi.santosa@xxxxxxxxx>]

Hi...

> can we figure out this 3G:1G split from process's  address map below?
More or less, yes. Check the highest address of stack (that means, the
beginning of the stack in x86 since it grows downward). You'll see it
reaches 0xC0000 0000 or 3GB. This is the user space part. Thus kernel
space = 4-3=1GB. There you go, 3:1.

> is the mem_init(which gets called from start_kernel) and which has the
> arch specific implementation does the split?

I can't really help you locating where exactly which kernel function
that did this, but IIRC recent kernel does this by making PAGE_OFFSET
selectable during kernel config. Thus grepping through Kconfig and
kernel headers should bring you the clue.

regards,

Mulyadi

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