devices.camkes: vm#.untyped_mmios: What does the integer after the addresses in this array represent?
Hi all,
As stated in the question, I'm not certain about how the integer part of the elements in the untyped_mmios array in devices.camkes are derived?
E.g. in the TX2 devices.camkes file:
vm0.untyped_mmios = [ "0x3886000:12", // GICV Iface. /* The purpose of these untyped regions is to force the untyped * allocator to treat this memory region as reserved so that when we * try to ensure that the VMM is placed into this region in RAM, it * will definitely be available for placement. * * This address pertains to guest-vm@f1000000 in the overlay DTS */ "0xF1000000:24", "0xF2000000:25", "0xF4000000:26", "0xF8000000:24", ];
I recognise that the range of addresses here covers the VM_RAM_SIZE specified, and so the pattern that emerges is:
24 --> 0x01000000 25 --> 0x02000000 26 --> 0x04000000
And so the above would cover the range 0xf1000000 --> 0xf9000000, which is the range of memory specified for the VM.
Is this simply a case of the integer representing double the value with each increment. E.g:
Integer
Int Rep
Hex
0
1
0x0000_0001
1
2
0x0000_0002
2
4
0x0000_0004
3
8
0x0000_0008
4
16
0x0000_0010
5
32
0x0000_0020
6
64
0x0000_0040
7
128
0x0000_0080
8
256
0x0000_0100
9
512
0x0000_0200
10
1024
0x0000_0400
11
2048
0x0000_0800
12
4096
0x0000_1000
13
8192
0x0000_2000
14
16384
0x0000_4000
15
32768
0x0000_8000
16
65536
0x0001_0000
17
131072
0x0002_0000
18
262144
0x0004_0000
19
524288
0x0008_0000
20
1E+06
0x0010_0000
21
2E+06
0x0020_0000
22
4E+06
0x0040_0000
23
8E+06
0x0080_0000
24
2E+07
0x0100_0000
25
3E+07
0x0200_0000
26
7E+07
0x0400_0000
27
1E+08
0x0800_0000
28
3E+08
0x1000_0000
29
5E+08
0x2000_0000
30
1E+09
0x4000_0000
31
2E+09
0x8000_0000
Thanks,
Ben Turner Senior Engineer Roke Manor Research Ltd Tel: +44 (0)1794 833721 ben.turner@roke.co.ukmailto:ben.turner@roke.co.uk
________________________________________ Roke Manor Research Limited, Romsey, Hampshire, SO51 0ZN, United Kingdom.Part of the Chemring Group. Registered in England & Wales. Registered No: 00267550 http://www.roke.co.uk _______________________________________ The information contained in this e-mail and any attachments is proprietary to Roke Manor Research Limited and must not be passed to any third party without permission. This communication is for information only and shall not create or change any contractual relationship. ________________________________________
Hi Ben,
As stated in the question, I'm not certain about how the integer part of the elements in the untyped_mmios array in devices.camkes are derived? "0xF1000000:24", "0xF2000000:25", "0xF4000000:26", "0xF8000000:24",
You are right that the numbers represent the size of the untyped mmios being created, 0xF1000000:24 -> [0xF1000000, 0xF1000000 + 0x1000000). In the example you gave, the four elements are defining a single ram region, but because the objects being created are seL4 untypeds that the vmm uses to construct the RAM device, there is an seL4 constraint that untyped objects can't be larger than their alignment. So camkes wouldn't be able to create an untyped object defined as: "0xF1000000:27" as this object would only have an alignment of 2^24 and seL4 would reject the retype invocation.
Hope this answers your question.
"Turner," == Turner, Ben ben.turner@roke.co.uk writes:
Turner,> Hi all, As stated in the question, I'm not certain about how Turner,> the integer part of the elements in the untyped_mmios array Turner,> in devices.camkes are derived?
It's a power-of-two, representing the size of the object. 2^12 is 4096 or 0x1000, 2^24 is 0x01000000
-
Chubb, Peter (Data61, Kensington NSW) -
Mcleod, Kent (Data61, Kensington NSW) -
Turner, Ben