memory region attribute CLI

[Eli Zaretskii]

> * create memory region:
> 
>         mem <start> <end> attribute [attribute ...]
> 
>   example:
>         (gdb) mem 0x00008000 0x0000FFFF ro 8
>         (gdb) mem 0x00007FF0 0x00007FFF rw
>         (gdb) mem 0x00007FE0 0x00007FEF wo 16
>         (gdb) mem 0x00007FD0 0x00007FDF ro

Could you please point to the discussions about this feature?  I find
it hard to understand what would be the usage of the memory regions.