Re: [Qemu-discuss] Qemu-system-sparc: What would I need to change to add functionality to save the nvram content between boots ?

[Programmingkid]

On Sep 13, 2015, at 7:20 PM, Bodo Eggert wrote:

> On Sun, 13 Sep 2015, Programmingkid wrote:
>> On Sep 13, 2015, at 5:50 PM, Bodo Eggert wrote:
>>> On Sun, 13 Sep 2015, Mark Cave-Ayland wrote:
>>>> On 11/09/15 19:01, Programmingkid wrote:
> 
>>>>> Mark, do you think it is possible for a QEMU command line option to
>>>>> actually load the
>>>>> saved OpenBIOS settings from a file and restore them into memory? I'm
>>>>> thinking something
>>>>> along the lines of -prom-memory <file name>. 
>>> 
>>>>> From memory the reason this hasn't been done is because the NVRAM
>>>> interface is used across multiple architectures and there hasn't been a
>>>> solution devised that would work well enough for all of them. Then again
>>>> as the BIOSs involved have continued to develop, it may be now that some
>>>> of the issues can now be solved so it never hurts to ask on the -devel 
>>>> list.
>>> 
>>> I'm wondering, why wouldn't it be enough to memmap a nvram file instead of 
>>> mallocing (or whatever) the memory area?
>> 
>> What advantage does mmap() have over malloc()? I think malloc() is a lot more
>> familiar to use than mmap().
> 
> The advantage is that it's file-backed (optionally, but intended here).  
> Everything you write into that memory area will be automatically 
> saved and restored just like a nvram should be. At least, that's what the 
> documentation promises, I never used it myself, therefore I ask.

You make mmap() sound good. Maybe we should use it.