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Date: Mon, 13 Jun 2011 14:03:40 +0200
From: Laurent Alfonsi <laurent.alfonsi@st.com>
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Subject: Re: [Qemu-devel] [PATCH] linux-user: Define AT_RANDOM to support
 target	dynamic linkers that do ASLR
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To: Cedric VINCENT <cedric.vincent@st.com>
Cc: Riku Voipio <riku.voipio@iki.fi>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Richard Henderson <rth@twiddle.net>

>>          unsigned char k_rand_bytes[16];
>>          elf_addr_t __user *u_rand_bytes;
>> ...
>>          /*
>>           * Generate 16 random bytes for userspace PRNG seeding.
>>           */
>>          get_random_bytes(k_rand_bytes, sizeof(k_rand_bytes));
>>          u_rand_bytes = (elf_addr_t __user *)
>>                         STACK_ALLOC(p, sizeof(k_rand_bytes));
>>          if (__copy_to_user(u_rand_bytes, k_rand_bytes, sizeof(k_rand_bytes)))
>>                  return -EFAULT;
>> ...
>>          NEW_AUX_ENT(AT_RANDOM, (elf_addr_t)(unsigned long)u_rand_bytes);
> It's clearer to me now, thanks.
It is fine with me, I also understand better now.
And this now brings me to another point : In that case, it might have 
sense to also add the auxv AT_RANDOM_SIZE.
     http://sources.redhat.com/ml/libc-alpha/2008-10/msg00016.html

>> I suggest at minimum a command-line argument to force a
>> particular AT_RANDOM value, for repeatability.
Yep, I agree.

Laurent.