I noticed the bug only recently, but checking with older Knoppix boot-cds, it seems to date back to about 2.6.9, where disk-access was generally slower, and hpa probably not detected at all) The symptom of the bug is, that an HPA is believed (by the kernel) to exist, and the capacity is believed to be one sector larger. When accessing that one last sector, the harddisk (rightly) reports an error, which causes the kernel to retry a few times (getting the same error each time) and finally the kernel switches off dma. The problem is in idedisk_read_native_max_address() and equivalently in idedisk_read_native_max_address_ext() in a line like this (near the end): addr++; /* since the return value is (maxlba - 1), we add 1 */ I believe that this is wrong, in so far as it is device-specific. My belief is, that what might need to be added instead is drive->sect0 or perhaps something completely different. This belief is based on that the addr++; works fine with some other harddisks in my reach (so obviously, adding one isn't always wrong), and that other people shared my problem as described in a newsgroup, found at: <http://tinyurl.com/ee7me> which redirects to <http://groups.google.com/group/linux.debian.user.german/browse_thread/thread/ab8980cb5ea0a9fb/7f475d3ce8f34211?tvc=2&q=linux+hpa+seagate+0x10> (german-language, but the dmesg-excerpts and patches speak for themselves) They suggest to comment out the "addr++;" altogether, which I don't think is good, but at least doesn't hurt, because a too-small value is ignored anyway lateron in idedisk_check_hpa(), so in worst case the hpa is disabled only partially (up to one sector). Please let me know what you think of it. People on the list: please Cc: avl@xxxxxxxx in this thread. - 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
