On Wednesday, April 30, 2014 10:12 PM, Catalin Marinas wrote:

On Wed, Apr 30, 2014 at 07:41:40AM +0100, Jungseok Lee wrote:

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On Tuesday, April 29, 2014 11:48 PM, Catalin Marinas wrote:

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On Tue, Apr 29, 2014 at 05:59:27AM +0100, Jungseok Lee wrote:

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--- a/Documentation/arm64/memory.txt
+++ b/Documentation/arm64/memory.txt

@@ -8,10 +8,11 @@ This document describes the virtual memory

layout used by the AArch64  Linux kernel. The architecture allows
up to 4 levels of translation  tables with a 4KB page size and up to 3 levels with a 64KB page

size.

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-AArch64 Linux uses 3 levels of translation tables with the 4KB
page -configuration, allowing 39-bit (512GB) virtual addresses for
both user -and kernel. With 64KB pages, only 2 levels of
translation tables are -used but the memory layout is the same.
+AArch64 Linux uses 3 levels and 4 levels of translation tables
+with the 4KB page configuration, allowing 39-bit (512GB) and
+48-bit
+(256TB) virtual addresses, respectively, for both user and kernel.
+With 64KB pages, only 2 levels of translation tables are used but
+the memory layout is the same.

Any reason why we couldn't use 48-bit address space with 64K pages (implying 3 levels)?

No technical reason.
Since 64K+3levels is not implemented in this set, I didn't add it.

Should 64K+3levels be prepared in this patchset?

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-AArch64 Linux memory layout with 64KB pages:
+AArch64 Linux memory layout with 4KB pages + 4 levels:
+
+Start			End			Size		Use
+-----------------------------------------------------------------------
+0000000000000000	0000ffffffffffff	 256TB		user
+
+ffff000000000000	ffff7bfffffeffff	~124TB		vmalloc

BTW, maybe as a separate patch we should change the "end" to be
exclusive. It becomes harder to modify (I've been through this a few times already ;)) and even

follow the changes.

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Does "exclusive" mean that 0000ffffffffffff is changed to 0001000000000000?
Or Does it mean that "End" column is dropped?

Not dropped but changed to 0001.... (the kernel already prints the memory layout in a similar way).

I see. I will make it as a separate patch.

Best Regards
Jungseok Lee