On Tuesday 26 May 2009 01:06:12 Frans Pop wrote: > On Tuesday 26 May 2009, Alan Cox wrote: > > > It's also not obvious (at least not to a dumb user like me) that > > > "ignore HPA limit" is equivalent to "preserving the Host Protected > > > Area" as the commit commit says. > > > > It isn't - its the exact reverse. > > Right. > > > Ignoring the HPA limit tells the kernel to ignore the system BIOS and > > firmware set defaults and to stomp the whole disk regardless. On a > > modern system thats almost always a really bad idea. Unfortunately on > > ancient boxes with disk jumpers set to lie about the disk size (32GB > > clipping etc) its the right thing. > > > > Having the same parameter in both stacks seems a good idea but really > > we need Tejun's patch exposing the values and then to propogate the hpa > > ignore into sysfs and trigger a revalidate of the disk if you change > > it. Libata has all the framework for that ready just needing the final > > bits. I don't see anything problematic in old IDE also having that > > interface. > > That also sounds as if it would better protect (or at least inform) > existing users who have file systems on disks where the HPA is currently > being ignored. > > Seems to me this whole issue would also be worth an LWN (BCCed) article to > raise awareness, explain the issue, maybe give practical info how to test > whether you're affected, and maybe add some advice to distributions how > to handle it. Seems to me like it's something that should be mentioned in > distribution release notes. Ironically, some distributions were a well aware of the problem, yet they chose to ignore it *twice* over the last few years. First time with the introduction of the default IDE HPA behavior of always giving the access to the full capacity of a disk and leaving decisions about HPA preservation/removal up to the installer & user. Second time when said distributions switched from IDE to libata (which uses the different default behavior as it limits the capacity to non-HPA part). Please note that no fancy sysfs support was needed to prevent the problem: both stacks (ide & libata) support HDIO_DRIVE_TASK ioctl which can be used to execute commands needed to retrieve/change HPA setting. Moreover the (much needed) work from Tejun doesn't help a tiny bit in case of people migrating their *working* setups from IDE to libata (at least in distro upgrade case this could have been handled by distro installer but see above) and hitting the compatibility issue mentioned in bug #13365. Anyway I'm putting all HPA fixes on hold as I have enough (thanks for your feedback on patches - all points are valid and I will address them if I ever take patches out of freezer). Thanks. Bart -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
