Re: [Xen-devel] Size limit on extra argument to xm create

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 12/10/2009 18:05, "Mick Jordan" <Mick.Jordan@xxxxxxx> wrote:

> On 10/ 9/09 11:30 PM, Keir Fraser wrote:
>> Since it's baked into the guest ABI, it's not expandable. It's rather likely
>> you'll have to live with only 1024 characters of boot parameters: the
>> horror!
>>   
> I realize that 1024 seems large enough for a traditional OS. In my Java
> Virtual Machine guest, I am faced with some applications that issue very
> large command lines, certainly in excess of 1024. There are workarounds,
> but it means I can't run certain apps out of the box.
>> The initial ram disk is just an 'module' you can load into guest memory for
>> interpretation by the guest kernel as it loads. Convention is to load it
>> into RAM immediately after the guest kernel, and place its address and size
>> into the mod_start/mod_len fields of start_info.
>>   
> I assume this is specified via the "ramdisk" configuration file option?

Yeah, so for example you can (ab)use the ramdisk option by writing your
super-long command line into a file, and then specify that file as a
ramdisk. And have a convention that your Java VM interprets a ramdisk as a
command line. You can stick whatever you like in that ramdisk file, and it
can be pretty much as big as you like.

 -- Keir



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