2013-09-10 06:01 keltezéssel, Robert Hancock írta:
On 09/08/2013 12:35 AM, Levente Kurusa wrote:
Hi,
I have been testing the Linux Kernel on a two year Toshiba NB100
netbook of mine, however when I enabled SATA compatibility/legacy mode
instead of AHCI mode in the BIOS, the kernel got stuck. I have pasted
the relevant dmesg piece along with a patch that fixes it temporarily.
What I suspect to be the cause is that the BIOS sets the device into
IDE mode, but it will report it as a SATA device and hence libata tries
to send ATA commands to it, which obviously makes it go bad. The patch
No, the commands are the same whichever mode the controller is in. The
problem is presumably something else, like maybe some kind of interrupt
routing problem when the controller is in legacy mode.
Yes, I see now.
fixes it, by adding a new field to ata_device called exce_cnt, which
counts how many exceptions have occured. After three exceptions, it
automatically disables the device. Also, please note this is my first
ever patch for the kernel :-)
The following dmesg is stuck in an infinite loop.
dmesg:
ata3: lost interrupt (Status 0x50)
ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
ata3.00: failed command: READ DMA
ata3.00: cmd c8/00:08:00:00:00/00:00:00:00:00/e0 tag 0 dma 4096 in
res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4
(timeout)
ata3.00: status: { DRDY }
ata3: soft resetting link
ata3.00: configured for UDMA/33 (no error)
ata3.00: device reported invalid CHS sector 0
ata3: EH complete
Patch that fixes the infinite loop:
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index f9476fb..eeedf80 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2437,6 +2437,14 @@ static void ata_eh_link_report(struct ata_link
*link)
ehc->i.action, frozen, tries_buf);
if (desc)
ata_dev_err(ehc->i.dev, "%s\n", desc);
+ ehc->i.dev->exce_cnt ++;
+ ata_dev_warn(ehc->i.dev, "Number of exceptions: %d\n",
ehc->i.dev->exce_cnt);
+ /**
+ * The device is failing terribly,
+ * disable it to prevent damage.
+ */
+ if(ehc->i.dev->exce_cnt > 2)
+ ata_dev_disable(ehc->i.dev);
} else {
ata_link_err(link, "exception Emask 0x%x "
"SAct 0x%x SErr 0x%x action 0x%x%s%s\n",
diff --git a/include/linux/libata.h b/include/linux/libata.h
index eae7a05..fa52ee6 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -660,7 +660,8 @@ struct ata_device {
u8 devslp_timing[ATA_LOG_DEVSLP_SIZE];
/* error history */
- int spdn_cnt;
+ int spdn_cnt; /* Number of speed_downs */
+ int exce_cnt; /* Number of exceptions that
happenned */
/* ering is CLEAR_END, read comment above CLEAR_END */
struct ata_ering ering;
};
This doesn't seem like a very good fix. It may prevent the apparent
infinite loop but will just prevent that device from functioning at all.
It would be better if we could figure out what was actually going wrong.
I have tested the problem with three different computers, all switched
to legacy/IDE/compatibility mode, and they didn't have this problem. Of
course, they could have been set to AHCI mode, and there the kernel
would boot normally. Feels strange, but so far I was only able to
reproduce the problem with a Toshiba MK8052GSX. On the topic of my
patch, I still don't see why a device which fails so terribly that it
reports 3 exceptions shouldn't be disabled. Like in this case, it could
cause infinite loops.
--
Regards,
Levente Kurusa
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