RE: [PATCH] Xen Grub-style boot loader

RE: [PATCH] Xen Grub-style boot loader

[Ian Pratt]

> It's a simple grub style ncurses application.  This is my 
> ncurses app so 
> it's probably even easier than what I did.  It parses a 
> grub.conf file 
> and let's a user pick an entry.

I think to be useful this would need to run within the guest domain such that the grub menu appeared over the guest console connection. We'd have to use something akin to a real bootloader (but 32bit) to pull in the image and jump at it. Using linux with a suitable initrd and kexec might be a good soloution.

I'm not sure that the interactive selection of kernels is the #1 requirement here -- I think its more about being able to read the kernel from the domain's file system, and to be able to control the command line options. 

Ian


-------------------------------------------------------
This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting
Tool for open source databases. Create drag-&-drop reports. Save time
by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc.
Download a FREE copy at http://www.intelliview.com/go/osdn_nl

Re: RE: [PATCH] Xen Grub-style boot loader

[Jacob Gorm Hansen]

Ian Pratt wrote:
>>It's a simple grub style ncurses application.  This is my 
>>ncurses app so 
>>it's probably even easier than what I did.  It parses a 
>>grub.conf file 
>>and let's a user pick an entry.
> 
> 
> I think to be useful this would need to run within the guest domain such that the grub menu appeared over the guest console connection. We'd have to use something akin to a real bootloader (but 32bit) to pull in the image and jump at it. Using linux with a suitable initrd and kexec might be a good soloution.
> 
> I'm not sure that the interactive selection of kernels is the #1 requirement here -- I think its more about being able to read the kernel from the domain's file system, and to be able to control the command line options. 

I have some code for pulling in a Linux ELF image via UIP-TCP under 
Xen1.3, unpacking it and jumping at it, if anyone is interested. The 
total bootloader binary is 30kb.

The networking driver needs to be ported to Xen 2.0, but otherwise it 
should just work.

Jacob


-------------------------------------------------------
This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting
Tool for open source databases. Create drag-&-drop reports. Save time
by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc.
Download a FREE copy at http://www.intelliview.com/go/osdn_nl

Re: [PATCH] Xen Grub-style boot loader

[Anthony Liguori]

Ian Pratt wrote:

>I think to be useful this would need to run within the guest domain such that the grub menu appeared over the guest console connection. We'd have to use something akin to a real bootloader (but 32bit) to pull in the image and jump at it. Using linux with a suitable initrd and kexec might be a good soloution.
>  
>
Making the console appear over the guest connection isn't hard while 
still having the boot loader be a dom0 process.  It's particularly easy 
if you make the console visible as a tty.  In the current Xend 
architecture, you would just dup the socket as the std(in|out) of the 
process and exec the boot loader before starting the domain.

I think the only real advantage to having it be a part of domain-U is 
that you avoid the problem with mounting a file system.  The more I 
think about it though the more of a security concerns worry me.  Long 
term, I think a domU loader is a better solution.  However, I think 
there's a large class of users where a dom0 boot loader would be just fine.

>I'm not sure that the interactive selection of kernels is the #1 requirement here -- I think its more about being able to read the kernel from the domain's file system, and to be able to control the command line options. 
>  
>
It's definitely not the #1 requirement but it's certainly useful.  You 
don't really need a boot loader to read the kernel from the domain's 
file system or to give the user the ability to control the command line.

Would you being willing to accept a boot loader that ran as a dom0 
process and exported it's screen through the console?  Even if it was 
only a temporary solution until a better boot loader was written?  I ask 
because I can probably code up the rest (I already can read the 
grub.conf off of a specified device) by tonight or tomorrow.

I think it would take more time than I could invest to do the dom0 
approach any time soon.  Unless of course someone else is willing to do 
it in which case I agree that the dom0 approach is superior :-)

Regards,
Anthony Liguori

>Ian
>
>  
>



-------------------------------------------------------
This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting
Tool for open source databases. Create drag-&-drop reports. Save time
by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc.
Download a FREE copy at http://www.intelliview.com/go/osdn_nl

Re: Re: [PATCH] Xen Grub-style boot loader

[Jeremy Katz]

On Thu, 2005-02-03 at 17:37 -0600, Anthony Liguori wrote:
> Would you being willing to accept a boot loader that ran as a dom0 
> process and exported it's screen through the console?  Even if it was 
> only a temporary solution until a better boot loader was written?  I ask 
> because I can probably code up the rest (I already can read the 
> grub.conf off of a specified device) by tonight or tomorrow.

I at least think that this would be an interesting point to start from.
And quite possibly interesting in a longer term.

Jeremy



-------------------------------------------------------
This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting
Tool for open source databases. Create drag-&-drop reports. Save time
by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc.
Download a FREE copy at http://www.intelliview.com/go/osdn_nl