On 01/12/2012 09:31 PM, Alan Stern wrote:
Judging by the log, the reader isn't able to handle such a large card.
It reported a total capacity of 0xffba7800 sectors, about 2 TB as shown
in the dmesg log. The correct value should have been somewhere around
0x03b9aca0. Then when the computer took the reader at its word and
asked for the contents of sector 0xffba7780, the reader flipped out,
requiring a reset. Things went downhill from there.
There are more devices with this problem, judging by Ondrej's email.
Shouldn't we then fall back to an alternative way of accessing the
device? I.e. do what the alternative OS does?
This is what it seems to do, judging by the times after which the device
is ready to use / is able to show the content (in the alternative OS).
The times before the content is shown in the alternative OS is as below:
- 4 secs - when using the laptop built-in card reader and a 32 GB SDHC card,
- 18 secs - when using this USB card reader and a 32 GB SDHC card,
- 3 secs - when using this USB card reader and a 2 GB card.
18 secs - this seems to suggest that the OS is spending extra time and
uses workarounds to access the device which doesn't work as a spec says.
With the 2-GB card, the reported capacity was 0x003cc000, which is
about right as shown in the dmesg log.
Unfortunately there is no way to override a device capacity. It
doesn't look like you'll be able to use this reader with that card.
Great.
By the way, what happens if you try to repartition the 32-GB card using
this reader under a different OS?
I'm not able to repartition it under Windows, in the USB card reader,
and in the built-in card reader.
I've repartitioned under Linux (laptop with a built-in SD/HC card reader).
With one, 2 GB partition, it still resets / doesn't work. Same with no
partitions at all.
--
Tomasz Chmielewski
http://wpkg.org
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