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
>