Re: [Qemu-devel] [PATCH] s390x: initialize virtio dev region

[Alexander Graf <agraf@suse.de>]

On 11/11/2011 05:44 PM, Peter Maydell wrote:
> On 11 November 2011 16:24, Alexander Graf<agraf@suse.de>  wrote:
>> On 11/11/2011 05:11 PM, Peter Maydell wrote:
>>> Yes, so that's option (2) and you need to be using a target_phys_addr_t.
>> But ram_size is ram_addr_t and is the ram size that I have available to use,
>> so it's exactly the address that I want. I don't see your point. Should go
>> jump through random useless hoops of doing
>>
>>   target_phys_addr_t ram_end = ram_size;
>>
>> just because there are some subtile semantic differences between the two
>> variables? They're integers at the end of the day. Both of them.
> Because handing a ram_addr_t to something that wants a target_phys_addr_t
> is a red flag that something might be wrong. (As is handing a variable
> called _size to something that wants an address.)
>
> Force in Newtons and Force in pound-feet are also both just integers
> at the end of the day, but that doesn't make them interchangeable:
> http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Communications_loss

Haha :). In this case, I pass ram_size indirectly to ram_alloc just a 
few lines above though, mapping it to 0. So while if this was normal 
device code I would agree with your reservation, in this case I don't 
think adding indirection buys us anything.


Alex