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

To: "Mick.Jordan@xxxxxxx" <Mick.Jordan@xxxxxxx>
Subject: Re: [Xen-devel] Size limit on extra argument to xm create
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Sat, 10 Oct 2009 07:30:49 +0100
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] Size limit on extra argument to xm create
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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!

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.

 -- Keir

On 09/10/2009 23:32, "Mick Jordan" <Mick.Jordan@xxxxxxx> wrote:

> On 10/ 9/09 01:31 PM, Keir Fraser wrote:
>> xen/include/public/xen.h:MAX_GUEST_CMDLINE should answer your question.
>> 
>>   
> Well it confirms the limit of 1024. So, if I recompiled Xen with, say,
> MAX_GUEST_CMDLINE=4096, would it "just work", or are there other issues?
> Of course, I really don't want a custom version of Xen, so it would be
> good if this value was increased in the standard build.
> 
> In passing I noticed the reference to "initial ram disk" in the image.
> Where can I find out more about this?
> 
> Mick
> 



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