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From: "Pedanekar, Hemant" <hemantp@ti.com>
To: "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>
Cc: "linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"Pedanekar, Hemant" <hemantp@ti.com>
Subject: Question on virtual memory layout: lowmem with memory hole
Date: Thu, 25 Aug 2011 09:35:07 +0530	[thread overview]
Message-ID: <2A3DCF3DA181AD40BDE86A3150B27B6B03B47E23FC@dbde02.ent.ti.com> (raw)

Hello,

While checking with memory hole configuration on OMAP3/TI816X (passing mem=x@y),
I see that the whole range from memory start till last bank including the hole
is labelled as 'lowmem' when kernel prints "Virtual kernel memory layout" during
boot.

E.g., on OMAP3 with mem=32M@0x80000000 mem=8M@0x87800000

(CASE 1)
 Memory: 32MB 8MB = 40MB total
 Memory: 28408k/28408k available, 12552k reserved, 0K highmem
 Virtual kernel memory layout:
     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
     fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)
     DMA     : 0xffc00000 - 0xffe00000   (   2 MB)
     vmalloc : 0xc8800000 - 0xf8000000   ( 760 MB)
     lowmem  : 0xc0000000 - 0xc8000000   ( 128 MB)
     modules : 0xbf000000 - 0xc0000000   (  16 MB)
       .text : 0xc0008000 - 0xc05ac2c8   (5777 kB)
       .init : 0xc05ad000 - 0xc05f8780   ( 302 kB)
       .data : 0xc05fa000 - 0xc06838d0   ( 551 kB)
        .bss : 0xc06838f4 - 0xc0bd8a14   (5461 kB)

Is this expected? 88MB space between two 'mem's seems to have lost. This also
means vmalloc space is lower compared to when a single mem=40M is passed.

E.g., with mem=40M

(CASE 2)
 Memory: 40MB = 40MB total
 Memory: 28412k/28412k available, 12548k reserved, 0K highmem
 Virtual kernel memory layout:
     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
     fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)
     DMA     : 0xffc00000 - 0xffe00000   (   2 MB)
     vmalloc : 0xc3000000 - 0xf8000000   ( 848 MB)
     lowmem  : 0xc0000000 - 0xc2800000   (  40 MB)
     modules : 0xbf000000 - 0xc0000000   (  16 MB)
       .text : 0xc0008000 - 0xc05ac2c8   (5777 kB)
       .init : 0xc05ad000 - 0xc05f8780   ( 302 kB)
       .data : 0xc05fa000 - 0xc06838d0   ( 551 kB)
        .bss : 0xc06838f4 - 0xc0bd8a14   (5461 kB)

Any way we can get virtual layout same in CASE 1 as in CASE 2?

Thanks.

   Hemant

WARNING: multiple messages have this Message-ID (diff)
From: hemantp@ti.com (Pedanekar, Hemant)
To: linux-arm-kernel@lists.infradead.org
Subject: Question on virtual memory layout: lowmem with memory hole
Date: Thu, 25 Aug 2011 09:35:07 +0530	[thread overview]
Message-ID: <2A3DCF3DA181AD40BDE86A3150B27B6B03B47E23FC@dbde02.ent.ti.com> (raw)

Hello,

While checking with memory hole configuration on OMAP3/TI816X (passing mem=x at y),
I see that the whole range from memory start till last bank including the hole
is labelled as 'lowmem' when kernel prints "Virtual kernel memory layout" during
boot.

E.g., on OMAP3 with mem=32M at 0x80000000 mem=8M at 0x87800000

(CASE 1)
 Memory: 32MB 8MB = 40MB total
 Memory: 28408k/28408k available, 12552k reserved, 0K highmem
 Virtual kernel memory layout:
     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
     fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)
     DMA     : 0xffc00000 - 0xffe00000   (   2 MB)
     vmalloc : 0xc8800000 - 0xf8000000   ( 760 MB)
     lowmem  : 0xc0000000 - 0xc8000000   ( 128 MB)
     modules : 0xbf000000 - 0xc0000000   (  16 MB)
       .text : 0xc0008000 - 0xc05ac2c8   (5777 kB)
       .init : 0xc05ad000 - 0xc05f8780   ( 302 kB)
       .data : 0xc05fa000 - 0xc06838d0   ( 551 kB)
        .bss : 0xc06838f4 - 0xc0bd8a14   (5461 kB)

Is this expected? 88MB space between two 'mem's seems to have lost. This also
means vmalloc space is lower compared to when a single mem=40M is passed.

E.g., with mem=40M

(CASE 2)
 Memory: 40MB = 40MB total
 Memory: 28412k/28412k available, 12548k reserved, 0K highmem
 Virtual kernel memory layout:
     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
     fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)
     DMA     : 0xffc00000 - 0xffe00000   (   2 MB)
     vmalloc : 0xc3000000 - 0xf8000000   ( 848 MB)
     lowmem  : 0xc0000000 - 0xc2800000   (  40 MB)
     modules : 0xbf000000 - 0xc0000000   (  16 MB)
       .text : 0xc0008000 - 0xc05ac2c8   (5777 kB)
       .init : 0xc05ad000 - 0xc05f8780   ( 302 kB)
       .data : 0xc05fa000 - 0xc06838d0   ( 551 kB)
        .bss : 0xc06838f4 - 0xc0bd8a14   (5461 kB)

Any way we can get virtual layout same in CASE 1 as in CASE 2?

Thanks.

   Hemant

             reply	other threads:[~2011-08-25  4:05 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-25  4:05 Pedanekar, Hemant [this message]
2011-08-25  4:05 ` Question on virtual memory layout: lowmem with memory hole Pedanekar, Hemant
2011-08-25 10:22 ` Russell King - ARM Linux
2011-08-25 10:22   ` Russell King - ARM Linux
2011-08-25 18:36   ` Pedanekar, Hemant
2011-08-25 18:36     ` Pedanekar, Hemant
2011-08-25 18:52     ` Russell King - ARM Linux
2011-08-25 18:52       ` Russell King - ARM Linux
2011-08-26 17:41       ` Pedanekar, Hemant
2011-08-26 17:41         ` Pedanekar, Hemant

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