> -----Original Message----- > From: Jan Beulich [mailto:jbeul...@suse.com] > Sent: 12 June 2017 12:12 > To: Paul Durrant <paul.durr...@citrix.com> > Cc: Julien Grall (julien.gr...@arm.com) <julien.gr...@arm.com>; Andrew > Cooper <andrew.coop...@citrix.com>; xen-devel(xen- > de...@lists.xenproject.org) <xen-de...@lists.xenproject.org>; 'Boris > Ostrovsky' <boris.ostrov...@oracle.com>; Juergen Gross > <jgr...@suse.com> > Subject: RE: [Xen-devel] debian stretch dom0 + xen 4.9 fails to boot > > >>> On 12.06.17 at 12:53, <paul.durr...@citrix.com> wrote: > >> -----Original Message----- > > [snip] > >> > > > >> > > What do you think it best to do for Xen 4.9? Hardcoding a 4k alignment > is > >> > > clearly easy and would work around this BIOS issue but, as you say, it > >> does > >> > > grow the image. Reverting Juergen's patch also works round the issue, > >> but > >> > > that is more by luck. Re-working the code is preferable, but I guess > >> > > it's > >> too > >> > > late to introduce such code-churn in 4.9. > >> > > >> > Reverting Jürgen's code is out of question with all the information > >> > you've gathered by now. I think re-working the EDD code slightly > >> > is the best option. Would you mind giving the attached patch a > >> > try? This still slightly grows the trampoline due to a few more > >> > instructions being needed, but should still be far better than > >> > embedding a whole 4k buffer (and then later finding a BIOS/disk > >> > combination which wants even more). Note that I've left a tiny > >> > bit of debugging code in there. > >> > > >> > >> Sure, I'll give that a go now. > >> > > > > That worked fine: > > > > (XEN) MBR[80] @ 85e0 (86000) > > But that's contrary to your earlier findings: Didn't you say simply > avoiding a 4k-boundary wasn't enough? And it certainly tells us > that this isn't a 4k drive (or at least the BIOS doesn't surface 4k > sectors) - I was really expecting a larger gap between the two > logged values. >
I'll go dump out the edd and double check what it is saying. My findings indicated that the problem seemed to be doing a read that spanned a 4k boundary caused a problem, so using 0x85e00 would be safe. The anomaly was that simply aligning the edd_info buffer and a 512 byte boundary and continuing to use that for reading did not work. > > so you can add my Tested-by to that. > > I.e. I'm not sure about this, as I'm still uncertain whether some > corruption didn't again occur. Of course APs coming up properly > would already be a relatively good sign (as now the permanent > part of the trampoline would be the predestined area for > corruption to occur in). > None of my findings ever indicated memory corruption (although there, of course, may have been some that I happened to miss), but rather misbehaviour of the int13 handler itself - either locking up, having odd effects (e.g. black screen), or both. Paul > Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
