hvc0 xvc0 "compatibility"?

hvc0 xvc0 "compatibility"?

[Dan Magenheimer]

I have a (RHEL5) guest that I alternate booting with a 2.6.18-xen
kernel and an upstream kernel.

Upstream uses hvc0 for the console and 2.6.18-xen uses xvc0.  To
switch between them, I manually modify /etc/inittab.  If I
forget to do this, I get no login prompt and have to destroy
the domain, restart selecting the other kernel, etc.

Do I recall a patch that allows one of these kernels to
handle both hvc0 and xvc0?  That would make my life easier.
Or is this something that can be done in userland?

Thanks,
Dan

Re: hvc0 xvc0 "compatibility"?

[Ian Campbell]

On Tue, 2009-06-23 at 16:00 -0400, Dan Magenheimer wrote:
> I have a (RHEL5) guest that I alternate booting with a 2.6.18-xen
> kernel and an upstream kernel.
> 
> Upstream uses hvc0 for the console and 2.6.18-xen uses xvc0.  To
> switch between them, I manually modify /etc/inittab.  If I
> forget to do this, I get no login prompt and have to destroy
> the domain, restart selecting the other kernel, etc.
> 
> Do I recall a patch that allows one of these kernels to
> handle both hvc0 and xvc0?  That would make my life easier.
> Or is this something that can be done in userland?

I think you are thinking of linux-2.6.18-xen.hg 762:a070228ac76e "add
hvc compatibility mode to xencons". If you add xencons=hvc to your
kernel command line then 2.6.18 will use hvc and since pvops will just
ignore the unknown option you won't need to keep switching stuff around.

Ian.

> 
> Thanks,
> Dan
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

RE: hvc0 xvc0 "compatibility"?

[Dan Magenheimer]

Yes, that's the one.  Thanks much for pointing it out.

> -----Original Message-----
> From: Ian Campbell [mailto:Ian.Campbell@citrix.com]
> Sent: Wednesday, June 24, 2009 2:24 AM
> To: Dan Magenheimer
> Cc: Xen-Devel (E-mail)
> Subject: Re: [Xen-devel] hvc0 xvc0 "compatibility"?
> 
> 
> On Tue, 2009-06-23 at 16:00 -0400, Dan Magenheimer wrote:
> > I have a (RHEL5) guest that I alternate booting with a 2.6.18-xen
> > kernel and an upstream kernel.
> > 
> > Upstream uses hvc0 for the console and 2.6.18-xen uses xvc0.  To
> > switch between them, I manually modify /etc/inittab.  If I
> > forget to do this, I get no login prompt and have to destroy
> > the domain, restart selecting the other kernel, etc.
> > 
> > Do I recall a patch that allows one of these kernels to
> > handle both hvc0 and xvc0?  That would make my life easier.
> > Or is this something that can be done in userland?
> 
> I think you are thinking of linux-2.6.18-xen.hg 762:a070228ac76e "add
> hvc compatibility mode to xencons". If you add xencons=hvc to your
> kernel command line then 2.6.18 will use hvc and since pvops will just
> ignore the unknown option you won't need to keep switching 
> stuff around.
> 
> Ian.
> 
> > 
> > Thanks,
> > Dan
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> 
>

Re: hvc0 xvc0 "compatibility"?

[Zhigang Wang]

Dan Magenheimer wrote:
> I have a (RHEL5) guest that I alternate booting with a 2.6.18-xen
> kernel and an upstream kernel.
> 
> Upstream uses hvc0 for the console and 2.6.18-xen uses xvc0.  To
> switch between them, I manually modify /etc/inittab.  If I

dan, can you write two lines include both hvc0 and xvc0 in your /etc/inittab?

thanks,

zhigang

> forget to do this, I get no login prompt and have to destroy
> the domain, restart selecting the other kernel, etc.
> 
> Do I recall a patch that allows one of these kernels to
> handle both hvc0 and xvc0?  That would make my life easier.
> Or is this something that can be done in userland?
> 
> Thanks,
> Dan
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

RE: hvc0 xvc0 "compatibility"?

[Dan Magenheimer]

> dan, can you write two lines include both hvc0 and xvc0 in 
> your /etc/inittab?

Apparently not.  With two "co" lines in /etc/inittab, I
can't get a console for either 2.6.18-xen or upstream.

> -----Original Message-----
> From: Zhigang Wang 
> Sent: Wednesday, June 24, 2009 5:43 AM
> To: Dan Magenheimer
> Cc: Xen-Devel (E-mail)
> Subject: Re: [Xen-devel] hvc0 xvc0 "compatibility"?
> 
> 
> Dan Magenheimer wrote:
> > I have a (RHEL5) guest that I alternate booting with a 2.6.18-xen
> > kernel and an upstream kernel.
> > 
> > Upstream uses hvc0 for the console and 2.6.18-xen uses xvc0.  To
> > switch between them, I manually modify /etc/inittab.  If I
> 
> dan, can you write two lines include both hvc0 and xvc0 in 
> your /etc/inittab?
> 
> thanks,
> 
> zhigang
> 
> > forget to do this, I get no login prompt and have to destroy
> > the domain, restart selecting the other kernel, etc.
> > 
> > Do I recall a patch that allows one of these kernels to
> > handle both hvc0 and xvc0?  That would make my life easier.
> > Or is this something that can be done in userland?
> > 
> > Thanks,
> > Dan
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> 
> 
>

Re: hvc0 xvc0 "compatibility"?

[Ferenc Wagner]

Dan Magenheimer <dan.magenheimer@oracle.com> writes:

>> dan, can you write two lines include both hvc0 and xvc0 in 
>> your /etc/inittab?
>
> Apparently not.  With two "co" lines in /etc/inittab, I
> can't get a console for either 2.6.18-xen or upstream.

You mustn't have two lines with the same ID.  So make that co1 and co2
for example.  After this, you'll still have the problem that init will
continuously trying to spawn getty on the nonexistent device, giving
you periodic error messages.  You can overcome this by using different
runlevels for example.  But it's best to override xencons.
-- 
Feri.