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Memory Layout
Posted: Tue May 30, 2006 7:48 pm
by omin0us
I am curious how you all have laid out your memory (when using virtual memory/paging).
ie:
0-4mb: identity mapped
0xc0000000 - 0xc0001000: kernel
0xc00b8000 - 0xc00a0000: video memory
0xd0000000 - 0xe0000000: kernel heap
...
etc.
I would like to know where other people are mapping their kernel, kernel stack, kernel heap, etc.
Re:Memory Layout
Posted: Tue May 30, 2006 8:31 pm
by Zeii[at-uni]
My design is odd.
However, the one constant thing across all 'tasks' and such, is that memory is identity mapped 0-1MB. (Kernel). (but even that maybe changed!)
Re:Memory Layout
Posted: Tue May 30, 2006 9:25 pm
by proxy
here is my memory map:
Code: Select all
0x0000000000000000 - 0x0000000000001000 : (unaccesible/null pointer detection)
0x0000000000001000 - 0x00000000c0000000 : (user space, to be divided up more)
0x00000000bfffd000 - 0x00000000c0000000 : primary thread stack of current process
0x00000000c0000000 - 0x00000000d0000000 : Identity map of lower 256 megs of mem including kernel
0x00000000c0000000 - 0x00000000c0000400 : Real Mode IVT (Interrupt Vector Table)
0x00000000c00b8000 - 0x00000000c00bffff : Video RAM
0x00000000c00c0000 - 0x00000000c00c7fff : Video Bios
0x00000000c0100000 - ? : Kernel (code/data/bss)
0x00000000e0000000 - 0x00000000e4000000 : Kernel Heap (64 megs)
0x00000000e5000000 - 0x00000000ed000000 : Video Linear Frame Buffer
0x00000000f0000000 - 0x00000000f0100000 : Temp page mapping
0x00000000ffc00000 - 0x00000000fffff000 : Page Tables as mapped by active page directory
0x00000000fffff000 - 0x0000000100000000 : Page Directory
Re:Memory Layout
Posted: Wed May 31, 2006 12:34 am
by Brendan
Hi,
My memory map/s go like this:
0x00000000 Process space
0x?0000000 Thread space
0x?0000000 Kernel space
0xFFFFFFFF End of kernel space
Thread space is always aligned on a 1 GB boundary, where it starts (and it's size) depends on the process (the header in the executable file).
Kernel space starts at different addresses for different kernels - 3.5 GB for 32 bit plain paging, 3 GB for PAE, and for 64 bit kernels it depends on the number of linear addressing bits supported by the CPU.
Kernel space and the highest chunk of "user space" is split into "sub-areas" for a variety of reasons.
Cheers,
Brendan
Re:Memory Layout
Posted: Wed May 31, 2006 5:34 pm
by Pyr0Mathic
this is mine, its very old build it like 4 years agoo before i knew how paging etc worked...
Kernell.
first gig is Paged directly to phisical mem. so: 0000.0000 - 3FFF.FFF
0000.0000 - 002F.FFFF ; kernell code, initial required Data-segs, all constant size etc...
0030.0000 - 003F.FFFF ; Tells me what phisical data is in use
0040.0000 - 007F.FFFF ; TSS or PageDir's..
0080.0000 - 3FFF.FFFF ; 4KB data
Paged memory:
4000.0000 - 7FFF.FFFF ; Kernell paged data seg.
8000.0000 - EFFF.FFFF ; Prog Paged Data seg.
that's about it, i know i trash the first 8 MB of the RAM.. only use half of it.
Regards.
PyroMathic