Mount root from SD card?
Bernd Walter
ticso at cicely7.cicely.de
Thu Jan 22 15:57:20 PST 2009
On Thu, Jan 22, 2009 at 04:26:33PM -0700, M. Warner Losh wrote:
> In message: <20090122230647.GN50103 at cicely7.cicely.de>
> Bernd Walter <ticso at cicely7.cicely.de> writes:
> : On Thu, Jan 22, 2009 at 03:57:41PM -0700, M. Warner Losh wrote:
> : > In message: <20090122180518.GK50103 at cicely7.cicely.de>
> : > Bernd Walter <ticso at cicely7.cicely.de> writes:
> : > : On Thu, Jan 22, 2009 at 08:02:14PM +0200, Alexander Motin wrote:
> : > : > Bernd Walter wrote:
> : > : > >As another point:
> : > : > >Is it possible to support SHDC with mci some day, or is there a special
> : > : > >hardware requirement for SDHC?
> : > : >
> : > : > SDHC (SD High Capacity) has just a different data addressing scheme (in
> : > : > 512bytes blocks instead of bytes). There is no special hardware
> : > : > requirements, only minor initialization differences. With present
> : > : > mmc/mmcsd modules SDHC should work fine on any controller.
> : > :
> : > : Good news - thank you for clearification.
> : >
> : > Now all we need to do is to enhance the boot blocks to be able to boot
> : > off the SDHC cards :)
> :
> : Yes, but since you wrote code to store the kernel inside SPI-flash
> : there is a useable workaround available ;-)
> : Full loader support would be more interesting than SDHC in boot code
> : anyway.
>
> Raj@ did some interesting work in this area for the marvel port...
I already noticed his work with great pleasure.
> : > BTW, I found and fixed the bug (at least I think so). We were
> : > assuming that all transfers were 512 bytes long. The newly used 16
> : > and 64 byte transfers broke that assumption, which is why things broke
> : > after Alexander's latest commits. There's still a small chance that
> : > there's something borked in the byte swapping code, but I kinda doubt
> : > it since I was able to mount root.
> : >
> : > svn commit r187603 is the fix.
> :
> : Great!
>
> Well, it doesn't work in 4-bit bus mode. Of course, I'm not sure it
> ever worked in 4-bit bus mode...
It never worked - I tried it a while back and had interesting results,
but it wasn't stable, which I asumed to be my bad knowledge on how this
should be implemented correctly.
Thanks to mav@ we have other controllers working and can test the
sdmmc part unrelated from mci.
Nevertheless: multiblock is the real speed issue.
My speed tests were very impressive, but because of mci problems data
were corrupted of course.
--
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
More information about the freebsd-arm
mailing list