Two questions about using GEM5 to model memory！

[flyeagle0]

1、I am using a SimpleCPU in SystemCall mode, and in the system I need to simulate, there is no virtual real address translation. How to turn off virtual real address translation in gem5? Every time my memory access instruction accesses an address, it is a physical address.

2、I want to know how to specify some memory addresses that can be accessed when my simulation system is initialized, without the need for a loaded program to specify. Under normal circumstances, an error will occur when a program accesses an address that has not been initialized.

[BobbyRBruce]

1. I'm not sure there's a way to "turn off" virtual addresses but you can manipulate them with the map funciton in the Process SimObject ("src/sim/Process.py"):

    /**
     * Maps a contiguous range of virtual addresses in this process's
     * address space to a contiguous range of physical addresses.
     * This function exists primarily to expose the map operation to
     * python, so that configuration scripts can set up mappings in SE mode.
     *
     * @param vaddr The starting virtual address of the range.
     * @param paddr The starting physical address of the range.
     * @param size The length of the range in bytes.
     * @param cacheable Specifies whether accesses are cacheable.
     * @return True if the map operation was successful.  (At this
     *           point in time, the map operation always succeeds.)
     */
    bool map(Addr vaddr, Addr paddr, int64_t size, bool cacheable = true);

2. I'm sorry, i don't know how this can be done.