[meta-ti] [PATCH] sdcard_image: align partitions with flash pages

[Jason Kridner]

On Thu, Oct 27, 2011 at 5:39 PM, Denys Dmytriyenko <denis at denix.org> wrote:
> On Wed, Oct 26, 2011 at 09:36:01PM -0400, Jason Kridner wrote:
>> See
>> http://sakoman.com/OMAP/a-script-for-partitioningformatting-a-bootable-sdmicrosd-card.html
>
> If I was Paul Menzel, I'd complain about non-descriptive description :)

Fair enough.  I thought giving the URL was better than taking the
credit for the ideas, but I could have extracted the ideas for the
change as well.  Do you need me to resubmit?  I'm comfortable with you
adding comments into the commit.

Or should I apply an additional patch to put comments into the code?

>
> Here's what I gathered from the above URL, which just gives the new script:
>
> # Modifications to align partitioning by Steve Sakoman
> # based on work by Arnd Bergmann
> # Align partitions for SD card performance/wear optimization
> # FAT partition size is 131072 sectors (64MB) less:
> #       MBR - 1 sector
> #       padding to align to the page size of the underlying flash - 127 sectors
> # so we start the first partition at sector 128 and make it 131072 - 128 = 130944 sectors
> # second partition starts at 131072 and continues to fill the card
>
> It would be nice to have that in the commit message just to explain the
> simingly random change of numbers below... :)
>
> BTW, Arnd Bergmann is the expert in SD card wear issues http://lwn.net/Articles/428584/
> and, if I remember correctly, he was showing some tests abusing whole bunch of
> SD cards at the last ELC.

Yeah, I sat down with Arnd and discussed it at ELC, which is why I
wanted to pick up the changes not only in mkcard as Steve did, but in
this class which is more convenient for people using OE to build SD
card images.

>
> --
> Denys
>
>> Signed-off-by: Jason Kridner <jdk at ti.com>
>> ---
>>  classes/sdcard_image.bbclass |    6 +++---
>>  1 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/classes/sdcard_image.bbclass b/classes/sdcard_image.bbclass
>> index 4ebc998..9e4a959 100644
>> --- a/classes/sdcard_image.bbclass
>> +++ b/classes/sdcard_image.bbclass
>> @@ -46,9 +46,9 @@ IMAGE_CMD_sdimg () {
>>       SIZE=$(/sbin/fdisk -l ${LOOPDEV} | grep Disk | grep bytes | awk '{print $5}')
>>       CYLINDERS=$(echo $SIZE/255/63/512 | bc)
>>       {
>> -     echo ,9,0x0C,*
>> -     echo ,,,-
>> -     } | /sbin/sfdisk -D -H 255 -S 63 -C ${CYLINDERS} ${LOOPDEV}
>> +     echo 128,130944,0x0C,*
>> +     echo 131072,,,-
>> +     } | /sbin/sfdisk -D -uS -H 255 -S 63 -C ${CYLINDERS} ${LOOPDEV}
>>
>>       # Prepare loop devices for boot and filesystem partitions
>>       BOOT_OFFSET=32256
>> --
>> 1.7.4.1
>>
>> _______________________________________________
>> meta-ti mailing list
>> meta-ti at yoctoproject.org
>> https://lists.yoctoproject.org/listinfo/meta-ti
>>
> _______________________________________________
> meta-ti mailing list
> meta-ti at yoctoproject.org
> https://lists.yoctoproject.org/listinfo/meta-ti
>