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Re: [Xen-devel] [PATCH v2 5/5] libxl, hvmloader: Don't relocate memory for MMIO hole



On 20/06/13 11:56, Jan Beulich wrote:
On 20.06.13 at 12:29, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> 
wrote:
On Thu, 20 Jun 2013, George Dunlap wrote:
On 20/06/13 11:12, Jan Beulich wrote:
However, if we want to be on the safe side and also make the
code work with a compiler that doesn't have a built-in _Bool, I'd
think

      allow_memory_relocate = !s || strtoll(s, NULL, 0);

would be the better statement (without any if() surrounding it,
and without the variable declaration having an initializer.
Doing this would effectively hide the "default" value.  This is bad because 1)
it's not clear what the default is to someone just scanning the code, 2) it's
hard to change.  (Consider how you'd modify the above statement if you wanted
to default to 0 instead.)
I would avoid the strtoll altogether:

if (s != NULL && s[0] != '0')
     allow_memory_relocate = 1;
else
     allow_memory_relocate = 0;
Let's not add hacks like this - a string of "0x1" ought to not be
mis-interpreted as meaning 0.

I'm pretty sure the xs protocol specifies "0" or "1" for booleans, so "0x1" would be undefined anyway.

 -George


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