Re: [Qemu-devel] best way to implement a "memclear" type instruction in TCG?

[Peter Maydell]

On 22 January 2014 19:06, Richard Henderson <address@hidden> wrote:
> On 01/22/2014 10:58 AM, Peter Maydell wrote:
>> In theory we could just find the pointer to the memory QEMU is backing
>> the guest RAM with and call memset on it...
>
> That's more or less what we do for the s390 insn XC.
> See mem_helper.c, especially mvc_fast_memset.

I deduce that those instructions can't have been tested
very thoroughly, because:

void cpu_physical_memory_unmap(void *buffer, hwaddr len,
                               int is_write, hwaddr access_len);

but
    cpu_physical_memory_unmap(dest_p, 1, len, len);
and
    cpu_physical_memory_unmap(dest_p, 1, len, len);
    cpu_physical_memory_unmap(src_p, 0, len, len);

Note the argument ordering error!

thanks
-- PMM