[Bug 1897680] [NEW] memory address over 0x2000_7ffc is not accessible in mps2-an505

[Bug 1897680] [NEW] memory address over 0x2000_7ffc is not accessible in mps2-an505

[Changho Choi]

Public bug reported:

I currently run qemu with the following options
`qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`

For some reason, memory address over 0x2000_7ffc is not accessible.
It can be tested in gdb as follow.

(gdb) x/x 0x20007ffc
0x20007ffc:	0x00000000
(gdb) x/x 0x20007ffd
0x20007ffd:	Cannot access memory at address 0x20007ffd
(gdb) x/x 0x20008000
0x20008000:	Cannot access memory at address 0x20008000

** Affects: qemu
     Importance: Undecided
         Status: New

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Title:
  memory address over 0x2000_7ffc is not accessible in mps2-an505

Status in QEMU:
  New

Bug description:
  I currently run qemu with the following options
  `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`

  For some reason, memory address over 0x2000_7ffc is not accessible.
  It can be tested in gdb as follow.

  (gdb) x/x 0x20007ffc
  0x20007ffc:	0x00000000
  (gdb) x/x 0x20007ffd
  0x20007ffd:	Cannot access memory at address 0x20007ffd
  (gdb) x/x 0x20008000
  0x20008000:	Cannot access memory at address 0x20008000

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[Bug 1897680] Re: memory address over 0x2000_7ffc is not accessible in mps2-an505

[Peter Maydell]

This is expected behaviour. The memory at 0x2000_0000 in this board is
the "FPGA block RAM", and there is only 32K of it, so it finishes at
0x2000_7fff, and attempts to access beyond that will fail because there
is no device or memory at the address immediately after it in the memory
map.

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Title:
  memory address over 0x2000_7ffc is not accessible in mps2-an505

Status in QEMU:
  New

Bug description:
  I currently run qemu with the following options
  `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`

  For some reason, memory address over 0x2000_7ffc is not accessible.
  It can be tested in gdb as follow.

  (gdb) x/x 0x20007ffc
  0x20007ffc:	0x00000000
  (gdb) x/x 0x20007ffd
  0x20007ffd:	Cannot access memory at address 0x20007ffd
  (gdb) x/x 0x20008000
  0x20008000:	Cannot access memory at address 0x20008000

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[Bug 1897680] Re: memory address over 0x2000_7ffc is not accessible in mps2-an505

[Peter Maydell]

PS: you don't need to pass "-cpu cortex-m33" as it is the default for
the mps2-an505 board, and you don't need to pass a -m argument either,
as 16MB is the fixed value for this board.

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Title:
  memory address over 0x2000_7ffc is not accessible in mps2-an505

Status in QEMU:
  New

Bug description:
  I currently run qemu with the following options
  `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`

  For some reason, memory address over 0x2000_7ffc is not accessible.
  It can be tested in gdb as follow.

  (gdb) x/x 0x20007ffc
  0x20007ffc:	0x00000000
  (gdb) x/x 0x20007ffd
  0x20007ffd:	Cannot access memory at address 0x20007ffd
  (gdb) x/x 0x20008000
  0x20008000:	Cannot access memory at address 0x20008000

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[Bug 1897680] Re: memory address over 0x2000_7ffc is not accessible in mps2-an505

[Peter Maydell]

(If you were just interested in having a large area of contiguous RAM,
the "PSRAM" is the largest lump on this board: it's 16MB starting at
0x8000_0000.)

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Title:
  memory address over 0x2000_7ffc is not accessible in mps2-an505

Status in QEMU:
  New

Bug description:
  I currently run qemu with the following options
  `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`

  For some reason, memory address over 0x2000_7ffc is not accessible.
  It can be tested in gdb as follow.

  (gdb) x/x 0x20007ffc
  0x20007ffc:	0x00000000
  (gdb) x/x 0x20007ffd
  0x20007ffd:	Cannot access memory at address 0x20007ffd
  (gdb) x/x 0x20008000
  0x20008000:	Cannot access memory at address 0x20008000

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Re: [Bug 1897680] [NEW] memory address over 0x2000_7ffc is not accessible in mps2-an505

[Philippe Mathieu-Daudé]

On 9/29/20 8:57 AM, Changho Choi wrote:
> Public bug reported:
> 
> I currently run qemu with the following options
> `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`
> 
> For some reason, memory address over 0x2000_7ffc is not accessible.
> It can be tested in gdb as follow.
> 
> (gdb) x/x 0x20007ffc
> 0x20007ffc:	0x00000000
> (gdb) x/x 0x20007ffd
> 0x20007ffd:	Cannot access memory at address 0x20007ffd

Works for me:

(gdb) x/xg 0x20007ff8
0x20007ff8:	0x0000000000000000

(gdb) x/xw 0x20007ffc
0x20007ffc:	0x00000000

(gdb) x/xh 0x20007ffe
0x20007ffe:	0x0000

(gdb) x/xb 0x20007fff
0x20007fff:	0x00

I suppose GDB uses 32-bit access size by default,
so requesting 32-bit at 0x20007ffd would access
out of bound memory.

> (gdb) x/x 0x20008000
> 0x20008000:	Cannot access memory at address 0x20008000

For TYPE_IOTKIT there is only 1 SRAM bank (see armsse_variants[])
initialized to SRAM_ADDR_WIDTH bits, which is 15 by default:

    DEFINE_PROP_UINT32("SRAM_ADDR_WIDTH", ARMSSE, sram_addr_width, 15),

So this MPC downstream region is a 32KB SRAM. The size looks correct.

> 
> ** Affects: qemu
>      Importance: Undecided
>          Status: New
> 

Re: [Bug 1897680] [NEW] memory address over 0x2000_7ffc is not accessible in mps2-an505

[Philippe Mathieu-Daudé]

On 9/29/20 8:57 AM, Changho Choi wrote:
> Public bug reported:
> 
> I currently run qemu with the following options
> `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`
> 
> For some reason, memory address over 0x2000_7ffc is not accessible.
> It can be tested in gdb as follow.
> 
> (gdb) x/x 0x20007ffc
> 0x20007ffc:	0x00000000
> (gdb) x/x 0x20007ffd
> 0x20007ffd:	Cannot access memory at address 0x20007ffd

Works for me:

(gdb) x/xg 0x20007ff8
0x20007ff8:	0x0000000000000000

(gdb) x/xw 0x20007ffc
0x20007ffc:	0x00000000

(gdb) x/xh 0x20007ffe
0x20007ffe:	0x0000

(gdb) x/xb 0x20007fff
0x20007fff:	0x00

I suppose GDB uses 32-bit access size by default,
so requesting 32-bit at 0x20007ffd would access
out of bound memory.

> (gdb) x/x 0x20008000
> 0x20008000:	Cannot access memory at address 0x20008000

For TYPE_IOTKIT there is only 1 SRAM bank (see armsse_variants[])
initialized to SRAM_ADDR_WIDTH bits, which is 15 by default:

    DEFINE_PROP_UINT32("SRAM_ADDR_WIDTH", ARMSSE, sram_addr_width, 15),

So this MPC downstream region is a 32KB SRAM. The size looks correct.

> 
> ** Affects: qemu
>      Importance: Undecided
>          Status: New
>

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https://bugs.launchpad.net/bugs/1897680

Title:
  memory address over 0x2000_7ffc is not accessible in mps2-an505

Status in QEMU:
  New

Bug description:
  I currently run qemu with the following options
  `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`

  For some reason, memory address over 0x2000_7ffc is not accessible.
  It can be tested in gdb as follow.

  (gdb) x/x 0x20007ffc
  0x20007ffc:	0x00000000
  (gdb) x/x 0x20007ffd
  0x20007ffd:	Cannot access memory at address 0x20007ffd
  (gdb) x/x 0x20008000
  0x20008000:	Cannot access memory at address 0x20008000

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Re: [Bug 1897680] Re: memory address over 0x2000_7ffc is not accessible in mps2-an505

[Changho Choi]

Thank you for all your kind answers and suggestions.
I also have confirmed that the memory address over 0x2000_8000 is not
accessible in the real board.

Regards,

Changho Choi

2020년 9월 29일 (화) 오후 6:25, Peter Maydell <1897680@bugs.launchpad.net>님이
작성:

> (If you were just interested in having a large area of contiguous RAM,
> the "PSRAM" is the largest lump on this board: it's 16MB starting at
> 0x8000_0000.)
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1897680
>
> Title:
>   memory address over 0x2000_7ffc is not accessible in mps2-an505
>
> Status in QEMU:
>   New
>
> Bug description:
>   I currently run qemu with the following options
>   `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`
>
>   For some reason, memory address over 0x2000_7ffc is not accessible.
>   It can be tested in gdb as follow.
>
>   (gdb) x/x 0x20007ffc
>   0x20007ffc:   0x00000000
>   (gdb) x/x 0x20007ffd
>   0x20007ffd:   Cannot access memory at address 0x20007ffd
>   (gdb) x/x 0x20008000
>   0x20008000:   Cannot access memory at address 0x20008000
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1897680/+subscriptions
>

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https://bugs.launchpad.net/bugs/1897680

Title:
  memory address over 0x2000_7ffc is not accessible in mps2-an505

Status in QEMU:
  New

Bug description:
  I currently run qemu with the following options
  `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`

  For some reason, memory address over 0x2000_7ffc is not accessible.
  It can be tested in gdb as follow.

  (gdb) x/x 0x20007ffc
  0x20007ffc:	0x00000000
  (gdb) x/x 0x20007ffd
  0x20007ffd:	Cannot access memory at address 0x20007ffd
  (gdb) x/x 0x20008000
  0x20008000:	Cannot access memory at address 0x20008000

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[Bug 1897680] Re: memory address over 0x2000_7ffc is not accessible in mps2-an505

[Peter Maydell]

** Changed in: qemu
       Status: New => Invalid

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Title:
  memory address over 0x2000_7ffc is not accessible in mps2-an505

Status in QEMU:
  Invalid

Bug description:
  I currently run qemu with the following options
  `qemu-system-aarch64 -machine mps2-an505 -cpu cortex-m33 -m 16`

  For some reason, memory address over 0x2000_7ffc is not accessible.
  It can be tested in gdb as follow.

  (gdb) x/x 0x20007ffc
  0x20007ffc:	0x00000000
  (gdb) x/x 0x20007ffd
  0x20007ffd:	Cannot access memory at address 0x20007ffd
  (gdb) x/x 0x20008000
  0x20008000:	Cannot access memory at address 0x20008000

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