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Re: [Qemu-devel] [PATCH] CMOS file support
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH] CMOS file support |
Date: |
Fri, 24 Sep 2010 14:47:19 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) |
Mathias Krause <address@hidden> writes:
> On 17.09.2010 15:27, Anthony Liguori wrote:
>> On 09/17/2010 01:50 AM, Mathias Krause wrote:
>>> Am 16.09.2010 19:20 schrieb Anthony Liguori:
>>>
>>>> Instead of using FILE, I'd suggest using a BlockDriver to read and write
>>>> the data.
>>>>
>>> I'll fix that as soon as I figured how to use this interface.
>>>
>>>
>>>> I think it would be very nice to add write support too so that writes to
>>>> CMOS were persisted across boots.
>>>>
>>> Indeed. Also I would like to have a command line interface like '-cmos
>>> cmos.bin' instead of the ugly '-global mc146818rtc.file=cmos.bin'. But
>>> I'm not aware how to create such an alias. Any pointers?
>>>
>>
>> Unfortunately, it's a little complicated although it should get better
>> in the future. The right way to do this today would be:
>>
>> -drive file=cmos.bin,if=none,id=nvram -global mc146818rtc.drive=nvram
>>
>> The use of -drive is historic. We'll have a better option in the future
>> that will look something like:
>>
>> -blockdev file=cmos.bin,id=nvram -global mc146818rtc.drive=nvram
>
> Well, I guess "better" lies in the eye of the beholder, then ;)
>
>
>> But in either case, I'd suggest adding an -nvram option that was:
>>
>> -nvram <filename>
>>
>> Which would do:
>>
>> drive_add(optarg, "if=none,id=nvram");
>>
>> And then in the RTC code, default drive to nvram.
>
> I managed to add the nvram option but how do I get a reference to the
> drive back in the RTC code? Would I just loop with drive_get(IF_NONE, 0,
> i) until the id of the returned drive is "nvram"? Doesn't sound right
> but I've found no better solution due to the lack of an
> drive_get_by_id() function.
Use DEFINE_PROP_DRIVE() to define mc146818rtc's property drive, and it's
automatic: qdev assigns a pointer to the BlockDriverState.
To access DriveInfo, use drive_get_by_blockdev(). I doubt you need
that.
[...]
Re: [Qemu-devel] [PATCH] CMOS file support, Anthony Liguori, 2010/09/16
Re: [Qemu-devel] [PATCH] CMOS file support, Markus Armbruster, 2010/09/24