Re: [Xen-devel] [PATCH] Don't attach needless options when launch pygrub

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Wed, 2010-07-14 at 10:36 +0100, Yu Zhiguo wrote:
> Ian Campbell wrote:
> > 
> > As far as I can see the --kernel and --ramdisk options end up in the
> > incfg map which only used in a handful of places, most of which just
> > extract incfg["args"]. The only places which do not do this are the
> > calls to sniff_solaris and sniff_netware both of which appear to make
> > use of incfg["kernel"] (but not incfg["ramdisk"]).
> > 
> > So it looks like specifying the kernel option in addition to bootloader
> > is infact useful if you are booting a Solaris or Netware domU but is
> > harmless/ignored otherwise. I think we need to continue to support this
> 
>  It seems that incfg will be returned directly if DomU is not Solaris,
> 
> def sniff_solaris(fs, cfg):
>     if not fs.file_exists("/platform/i86xpv/kernel/unix"):
>         return cfg
> 
> 
>     chosencfg = sniff_solaris(fs, incfg)
> 
>  So, incfg change to chosencfg and then will be used.

Oh yes, this stuff seems needlessly complex, or at least prone to
misreading, by me at least ;-)

You are right that chosencfg will be updated by sniff_solaris to be the
same as incfg if Solaris is not present (similarly for netware). 
Eventually we do "fs.open_file(chosencfg["kernel"]).read()" i.e. the
specified kernel from incfg will be read from the guest filesystem, as I
first expected.

All this is long standing behaviour, remind me why do you want to change
it?
[...]
>  What about copy the specified 'kernel' from DomU to a temp file.
> If there are 'bootloader' but no 'kernel', pygrub will copy and create temp 
> file.
> We can do the same things.

I think this is the current behaviour.

Ian.



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