On Mon, Apr 01, 2013 at 01:59:15PM +0800, Wei Xu wrote:> Hi Konrad, > I''d like to consult you some questions about the Xen Console, i''m > investigating it recently, i take some test on Linux(Fedora) hvm guest, it > works good. (Xen-4.1.3 and Linux 3.5.0). > > The most confused question of me is why did Xen Console come to mind in the > early date, What''s the requirement? Was it going to replace the emulated > serial by qemu, or just an additional way to access the guest with high > performance or sth other? > > I have post this in the xen-devel mail list and got some useful answer,Then lets add CC to it again.> since you are the expert about it, I''d like to consult you for the original > answer, thanks.The answer is ''additional way to access the guest without having to emulate the serial port''> > Regards, > Wei
On Mon, Apr 1, 2013 at 8:47 PM, Konrad Rzeszutek Wilk < konrad.wilk@oracle.com> wrote:> On Mon, Apr 01, 2013 at 01:59:15PM +0800, Wei Xu wrote: > > Hi Konrad, > > I''d like to consult you some questions about the Xen Console, i''m > > investigating it recently, i take some test on Linux(Fedora) hvm guest, > it > > works good. (Xen-4.1.3 and Linux 3.5.0). > > > > The most confused question of me is why did Xen Console come to mind in > the > > early date, What''s the requirement? Was it going to replace the emulated > > serial by qemu, or just an additional way to access the guest with high > > performance or sth other? > > > > I have post this in the xen-devel mail list and got some useful answer, > > Then lets add CC to it again. > > since you are the expert about it, I''d like to consult you for the > original > > answer, thanks. > > The answer is ''additional way to access the guest without having to emulate > the serial port'' > > Thanks.So this will improve the performance a lot on both Dom0 and DomU side, since the speed is not very critical when accessing a guest via console, I guess the most important benefit is to reduce the cpu cost of dom0 when emulating the serial port, is it or sth other? I have talked to stefano and he told the early printk is not supported by HVM guest while it''s available for PV guest with "earlyprintk=xen" indicated in kernel boot up parameters, so is there any concern to support it in the future? or is this worth to do?> Regards,> > Wei >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
On Mon, Apr 01, 2013 at 09:16:04PM +0800, Wei Xu wrote:> On Mon, Apr 1, 2013 at 8:47 PM, Konrad Rzeszutek Wilk < > konrad.wilk@oracle.com> wrote: > > > On Mon, Apr 01, 2013 at 01:59:15PM +0800, Wei Xu wrote: > > > Hi Konrad, > > > I''d like to consult you some questions about the Xen Console, i''m > > > investigating it recently, i take some test on Linux(Fedora) hvm guest, > > it > > > works good. (Xen-4.1.3 and Linux 3.5.0). > > > > > > The most confused question of me is why did Xen Console come to mind in > > the > > > early date, What''s the requirement? Was it going to replace the emulated > > > serial by qemu, or just an additional way to access the guest with high > > > performance or sth other? > > > > > > I have post this in the xen-devel mail list and got some useful answer, > > > > Then lets add CC to it again. > > > since you are the expert about it, I''d like to consult you for the > > original > > > answer, thanks. > > > > The answer is ''additional way to access the guest without having to emulate > > the serial port'' > > > > Thanks. > > So this will improve the performance a lot on both Dom0 and DomU side, > since the speed is not very critical when accessing a guest via console, I > guess the most important benefit is to reduce the cpu cost of dom0 when > emulating the serial port, is it or sth other?Sure. But as you said - you don''t use the console that often.> > I have talked to stefano and he told the early printk is not supported by > HVM guest while it''s available for PV guest with "earlyprintk=xen" > indicated in kernel boot up parameters, so is there any concern to support > it in the future? or is this worth to do?Correct. It could be supported, but it is more of a diagnostic tool (earlyprintk that is it). And as such you can also just use ''earlyprintk=serial'' to help with that.
On Monday, April 1, 2013, Konrad Rzeszutek Wilk wrote:> On Mon, Apr 01, 2013 at 09:16:04PM +0800, Wei Xu wrote: > > On Mon, Apr 1, 2013 at 8:47 PM, Konrad Rzeszutek Wilk < > > konrad.wilk@oracle.com <javascript:;>> wrote: > > > > > On Mon, Apr 01, 2013 at 01:59:15PM +0800, Wei Xu wrote: > > > > Hi Konrad, > > > > I''d like to consult you some questions about the Xen Console, i''m > > > > investigating it recently, i take some test on Linux(Fedora) hvm > guest, > > > it > > > > works good. (Xen-4.1.3 and Linux 3.5.0). > > > > > > > > The most confused question of me is why did Xen Console come to mind > in > > > the > > > > early date, What''s the requirement? Was it going to replace the > emulated > > > > serial by qemu, or just an additional way to access the guest with > high > > > > performance or sth other? > > > > > > > > I have post this in the xen-devel mail list and got some useful > answer, > > > > > > Then lets add CC to it again. > > > > since you are the expert about it, I''d like to consult you for the > > > original > > > > answer, thanks. > > > > > > The answer is ''additional way to access the guest without having to > emulate > > > the serial port'' > > > > > > Thanks. > > > > So this will improve the performance a lot on both Dom0 and DomU side, > > since the speed is not very critical when accessing a guest via console, > I > > guess the most important benefit is to reduce the cpu cost of dom0 when > > emulating the serial port, is it or sth other? > > Sure. But as you said - you don''t use the console that often. > > > > I have talked to stefano and he told the early printk is not supported by > > HVM guest while it''s available for PV guest with "earlyprintk=xen" > > indicated in kernel boot up parameters, so is there any concern to > support > > it in the future? or is this worth to do? > > Correct. It could be supported, but it is more of a diagnostic tool > (earlyprintk > that is it). > And as such you can also just use ''earlyprintk=serial'' to help with that. >> Got it，thanks._______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel