XO Debugging tips


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SD Card

Specially useful for XO-1.5

Retrieve internal SD card manufacturer

From Linux

find /sys -name oemid | xargs cat 

From OFW (Q3A49 and newer)

ok select int:0
ok show-cid

On older OFW try

ok dev /sd  patch get-cid get-csd attach-card  select int:0  " cid" $call-parent 10 dump

Interpreting the dump is not trivial. WMB dixit: "One of the fields is an enumerated hex number, another is a two-ascii character assigned ID (stored backwards), another is a 5-byte arbitrary ascii string (stored backwards), another is a BCD two-nibble version number, another is a 12-bit BCD code date, and another is a 4-byte serial number"

OEMID list

  • ADATA or 0x4144 "AD"
  • Kingston 0x544d "TM"
  • SanDisk 0x5344 "SD" or 0x534d "SM" (I think that SM means the card was made by Samsung - wmb)
  • Panasonic 0x5041 "PA"
  • Transcend 0x5365 "SV"

I have seen MicroSD cards that were labeled as Transcend, but with the same electronic ID as SanDisk - wmb.

Get performance timings

See SD_and_USB_FLASH_Drive_Performance for more info. With XO-1.5 Q3A50 or later, XO-1 Q2E45 or later, but not XO-1.75 or XO-4, test the internal SD card with:

ok .speed int:0

For external SD card,

ok .speed ext:0


Timing commands in OFW


ok t( yourcommand )t

For example you can time an fs-update command:

ok t( fs-update u:\os111.zd )t

this is redundant however -- fs-update reports its timings at the end of the run.

Timing reads from USB in OFW

To check that USB read times aren't slowing down fs-update, you

 ok dev fsdisk  : write-blocks-end  ;  : erase-blocks 2drop ;  : write-blocks-start 3drop 0 ;  dend  fs-update u:\osXXX.zd

The first command directs redirects writes to SD into /dev/null, keeping everything else the same. fs-update tries to overlap reads and writes, so adding read time + write time doesn't give you the answer, but if you find that the null-write case exceeds your normal fs-update timings, then USB read time is a factor.

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