Hi experts,

I tried to allocate a physical memory address in Linux Kernel, and pass the memory address to tf-a using smc call. As I asked in previous mails (https://lists.trustedfirmware.org/archives/list/tf-a@lists.trustedfirmware.o...), tf-a can not access the physical memory address directly, so I try to use the `mmap_add_dynamic_region_alloc_va` function in `xlat_table_v2` Library, and map the physical memory in tf-a.

After calling the function, It does return a new virtual memory address, but I still failed to access the address, is there any details I have missed? Here is the code:

```

NOTICE("phys_addr: 0x%lx, virt_addr: 0x%lx\n", phys_addr, virt_addr);     int rc = mmap_add_dynamic_region_alloc_va(phys_addr, ptr_virt_addr, size, MT_NS | MT_RW_DATA);     if (rc) {         WARN("Failed to map memory at 0x%lx: %d\n", phys_addr, rc);         return;     }     NOTICE("virt_addr_el3: 0x%lx\n", virt_addr_el3);     NOTICE("virt_addr_el3[0] = 0x%x\n", *((uint32_t *)virt_addr_el3));

```

Here is the output:

```

NOTICE:  phys_addr: 0x40f0000, virt_addr: 0xffff0000040f0000 NOTICE:  mm.base_va: 0 NOTICE:  mm.base_va: 100000000 NOTICE:  virt_addr_el3: 0x100000000 [   38.540464] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [   38.546584] rcu:     4-...0: (1 ticks this GP) idle=4224/1/0x4000000000000000 softirq=125/125 fqs=2625 [   38.555651]  (detected by 0, t=5252 jiffies, g=-779, q=16 ncpus=8) [   38.561843] Task dump for CPU 4: [   38.565075] task:main            state:R  running task stack:0     pid:195   ppid:181    flags:0x00000002 [   38.575015] Call trace: [   38.577464]  __switch_to+0xe4/0x160 [   38.580975]  0x42

```

I would be grateful for any advice or suggestions you may have.

Sincerely,

Feifan