> -----Original Message----- > From: Xen-devel [mailto:xen-devel-boun...@lists.xen.org] On Behalf Of Jan > Beulich > Sent: Friday, May 06, 2016 8:54 AM > To: Zytaruk, Kelly > Cc: xen-devel@lists.xen.org > Subject: Re: [Xen-devel] Debugging Xen early boot > > >>> On 06.05.16 at 14:31, <kelly.zyta...@amd.com> wrote: > > As for the other question I am still curious as to how to debug early Xen. > > How was __start_xen written and tested, what sort of tools were used > > to debug it and get it working right? > > I don't know how it was done here, but having been through the exercise of > debugging early boot code in other environments, I can only say: Get creative. > E.g. leverage whatever storage you have that persists across at least a warm > reboot. Depending on system I have found e.g. video RAM or some of the I/O > ports in the 0x80-0x8f range usable. I also recall that on one specific box I > had to > resort to using some of the CMOS non-volatile RAM or even the RTC registers > that don't change rapidly.
Ouch! Sounds painful. Looks like I had better hope that everything works fine up until the end of the init of the 16550s :( > > > What do I do in situations where I absolutely can't get serial > > working properly? > > Get serial working properly ;-) ? Or try USB (EHCI). Or use text mode video > output. > > Jan > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
