[PATCH 1/2] ARM: calculate VMALLOC_END by probing inmdesc->map_io()

-----Original Message-----
From: Nicolas Pitre [mailto:nico at fluxnic.net]
Sent: Sunday, January 23, 2011 7:48 PM
To: Santosh Shilimkar
Cc: Eric Miao; Russell King - ARM Linux; linux-arm-
kernel at lists.infradead.org
Subject: RE: [PATCH 1/2] ARM: calculate VMALLOC_END by probing
inmdesc->map_io()

[...]

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Can we possibly get away with a global VMALLOC_END?  What if we

were

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to
decide it is fixed at 0xf0000000 for everyone?

Which would potentialy shrink the lowmem and vmalloc area. With
current flexibility of adjustable VMALLOC_END, in 1G:3G model,
we managed to  have almost ~ 896 MB virtual space available
for lowmem + vmalloc. So keeping 128MB for vmalloc ~768MB of
memory can be directly addressable without highmem support.

OK, I just wanted to see if people do think that the simplicity of a
global definition would have made the per-architecture flexibility
irrelevant.  But looking at some of the mappings it seems that quite
a
lot of virtual space wastage would be imposed in some cases.

Yep.

Plus, moving vmalloc_end to the machine record is almost as simple
while
preserving the current flexibility.

As long we can maintain current flexibility, there shouldn't be
any problem.

Regards,
Santosh