sata_mv: improve warnings about Highpoint RocketRAID 23xx cards

Improve the existing boot/load time warnings from sata_mv
for Highpoint RocketRAID 23xx cards, based on new knowledge
about where the BIOS likes to overwrite sectors with metadata.

Harmless to us, but very useful for end users.

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 25 insertions, 5 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index fe0105d35bae..37b850ae0845 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -2506,11 +2506,31 @@ static int mv_chip_id(struct ata_host *host, unsigned int board_idx)
                 if (pdev->vendor == PCI_VENDOR_ID_TTI &&
                     (pdev->device == 0x2300 || pdev->device == 0x2310))
                 {
-                        printk(KERN_WARNING "sata_mv: Highpoint RocketRAID BIOS"
-                                " will CORRUPT DATA on attached drives when"
-                                " configured as \"Legacy\".  BEWARE!\n");
-                        printk(KERN_WARNING "sata_mv: Use BIOS \"JBOD\" volumes"
-                                " instead for safety.\n");
+                        /*
+                         * Highpoint RocketRAID PCIe 23xx series cards:
+                         *
+                         * Unconfigured drives are treated as "Legacy"
+                         * by the BIOS, and it overwrites sector 8 with
+                         * a "Lgcy" metadata block prior to Linux boot.
+                         *
+                         * Configured drives (RAID or JBOD) leave sector 8
+                         * alone, but instead overwrite a high numbered
+                         * sector for the RAID metadata.  This sector can
+                         * be determined exactly, by truncating the physical
+                         * drive capacity to a nice even GB value.
+                         *
+                         * RAID metadata is at: (dev->n_sectors & ~0xfffff)
+                         *
+                         * Warn the user, lest they think we're just buggy.
+                         */
+                        printk(KERN_WARNING DRV_NAME ": Highpoint RocketRAID"
+                                " BIOS CORRUPTS DATA on all attached drives,"
+                                " regardless of if/how they are configured."
+                                " BEWARE!\n");
+                        printk(KERN_WARNING DRV_NAME ": For data safety, do not"
+                                " use sectors 8-9 on \"Legacy\" drives,"
+                                " and avoid the final two gigabytes on"
+                                " all RocketRAID BIOS initialized drives.\n");
                 }
         case chip_6042:
                 hpriv->ops = &mv6xxx_ops;