> -----Original Message----- > From: Anthony PERARD [mailto:anthony.per...@citrix.com] > Sent: 21 March 2019 17:23 > To: Paul Durrant <paul.durr...@citrix.com> > Cc: xen-devel@lists.xenproject.org; Konrad Rzeszutek Wilk > <konrad.w...@oracle.com> > Subject: Re: [Xen-devel] [PATCH] public/io/blkif.h: make the comments on > "sectors" self-consistent > > > > I think this is how the currents implementations are working: > > > media/disk size = "sectors" * "sector-size" > > > then, "sectors" and "sector-size" are never used again. > > > > Not true, unfortunately. At least the Windows frontends are (mis)coded to > > use sector numbers > directly in blkif_request_t and blkif_request_segment rather than re-scaling > to 512 bytes, so setting > sector-size != 512 will certainly make them misbehave according to the > protocol. This can, of course, > be fixed but I think we're at point where the only safe way to set a larger > sector-size would be to > have the frontend write an 'I'm not broken' flag into xenstore that the > backend reads before setting > sector-size (and if that means that the backend has to do read-modify-write > cycles for an underlying > storage device with a larger logical block size then so be it). > > So, hard-coding "sector-size" to 512 in blkif.h sound good to me.
Ok, I'll send a v2 that does that. I think it best if I also include a specification my proposed 'I'm not broken' flag so a frontend can enable a backend to set a non-512 sector size. Paul > > -- > Anthony PERARD _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
