.kernel. Where has my ram gone?

Question

[    0.000000] Memory: 256MB = 256MB total
[    0.000000] Memory: 171736k/171736k available, 90408k reserved, 0K highmem
[    0.000000] Virtual kernel memory layout:
[    0.000000]     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
[    0.000000]     fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)
[    0.000000]     vmalloc : 0xd0800000 - 0xff000000   ( 744 MB)
[    0.000000]     lowmem  : 0xc0000000 - 0xd0000000   ( 256 MB)
[    0.000000]     pkmap   : 0xbfe00000 - 0xc0000000   (   2 MB)
[    0.000000]     modules : 0xbf000000 - 0xbfe00000   (  14 MB)
[    0.000000]       .text : 0xc0008000 - 0xc048d000   (4628 kB)
[    0.000000]       .init : 0xc048d000 - 0xc04b2000   ( 148 kB)
[    0.000000]       .data : 0xc04b2000 - 0xc04f7400   ( 277 kB)
[    0.000000]        .bss : 0xc04f7424 - 0xc0593f68   ( 627 kB)

I have an arm sun8i device with the 3.4.39 kernel. Available memory is only 256MB but the chip on the board is 2gb in size. Booted a kernel with highmem=y enabled but the problem remains. What is going on here? Lomem is capped at 256MB, can I even allocate the 700mb block? I thought lomem should include the vmalloc block.

What device is it? Are you sure the chip is supposed to be 2 GB (bytes), and not 2 Gb (bits)? — ilkkachu, Sep 22 '16 at 22:28
The exact chip is: H5TQ2G63FFR device is close to allwinner H3. — gamut, Sep 22 '16 at 22:30

score 5 · Accepted Answer · edited Sep 23 '16 at 16:46

5

Googling around for the chip you mentioned in comments, the H5TQ2G63FFR is a 2 Gb (gigabit) chip, so it only has 256 MB (megabytes) of memory.

The H5TQ2G83FFR-xxC, H5TQ2G63FFR-xxC, [...] are a 2,147,483,648-bit CMOS Double Data Rate III (DDR3) Synchronous DRAM, [...]

(quote from this PDF. )

It's not uncommon for memory chips to be specified in bits, as you could put eight of those together to make a 2 GB memory stick. (More chips can make a wider data path, depends on the system/processor how wide it should be.)

edited Sep 23 '16 at 16:46

Jeff Schaller

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answered Sep 22 '16 at 23:34

ilkkachu

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thank you. but where is vmalloc : 0xd0800000 - 0xff000000 ( 744 MB) from? there is no swap file. – gamut Sep 23 '16 at 03:28
That is just part of the (kernel) virtual address space - it isn't actual memory. – Murray Jensen Sep 23 '16 at 09:12

.kernel. Where has my ram gone?

1 Answers1