[Pkg-xen-devel] Re: Bug#390862: -bigmem version of xen kernels is really needed

[Pasi Kärkkäinen]

On Wed, Dec 13, 2006 at 09:19:12AM +0200, Pasi Kärkkäinen wrote:
> On Tue, Dec 12, 2006 at 03:59:13PM +0100, Ralph Passgang wrote:
> > Am Dienstag, 12. Dezember 2006 10:54 schrieb Nikita V. Youshchenko:
> > > What about idea not to *add* pae versions of xen kernels, but to *replace*
> > > non-pae versions with pae versions?
> > 
> > I don't think that debian should ship only pae-enabled kernels, because this 
> > has some disadvantages:
> > 
> > - the slowdown, even if it's minimal, I personaly don't want to get forced to 
> > use it.
> > 
> > - only pae-enabled system can use xen in 32bit mode, cpu's without pae cannot 
> > use xen at all! Not every cpu/bios is able to handle pae. 
> > (see "cat /proc/cpuinfo" for your cpu and check your bios settings if you are 
> > not sure).
> > 
> > - I had some trouble with pae on standard server hardware (in combination with 
> > xen) in the past. I think pae can make your system less stable (in rare 
> > cases).
> > 
> > My personal conclussion: pae is only a dirty hack. use it if you must, 
> > otherwise a non pae-enabled kernel/os is better.
> > 
> > I think debian should normal AND pae-enabled kernels, or maybe have the kernel 
> > decice that on boottime automaticly (if that's possible).
> > 
> > ah, and I don't get the "distribution compatibiltiy" point.
> > If your domU system is debian based, then you will use the non-pae kernel from 
> > etch and all your domUs also can use the same kernel. It doesn't matter if 
> > domU is also debian or fedora or something else, they should work with a 
> > debian kernel...
> > The same is true for a dom0 based on fedora and debian as domU. Use the same 
> > kernel (the one that gets shipped with the dom0 distribution) and use that 
> > for your debian domUs, too.
> > 
> > For compatibility it's more important that every distribution uses udev (for 
> > example) and not the depricated hotplug system.
> > 
> > just my 5 cent ;-P
> > 
> > --Ralph
> > 
> 
> I see it differently; I would like to use distribution/vendor provided
> kernels as much as possible.. saves from a lot of headaches. Redhat/fedora
> kernels for example have a lot of features/patches you don't (yet) have in
> vanilla or debian kernels.. 
> 

Not directly related to this, but this is why redhat decided to go for
pae-only:

https://www.redhat.com/archives/rhelv5-beta-list/2006-December/msg00068.html

"the decision to only support PAE capable hosts was made at the end of the
FC5 cycle. The majority (if not all)  of server in customer
datacenters/environments are PAE capable today and the only edge case for
non-PAE support would have been "older" laptops which do not yet have PAE
capable processors.  It also would have been an additional burden for QA/QE
to test/certify older non-PAE capable servers.  As the use case for Xen is
certainly geared towards servers and not laptops this made a lot of sense."

-- Pasi
       
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