Sorry to have missed the CC ---------- Forwarded message ---------- From: madhukesh s <[EMAIL PROTECTED]> Date: Thu, Oct 16, 2008 at 6:58 PM Subject: Re: Davinci-linux-open-source Digest, Vol 34, Issue 56 To: Phil Quiney <[EMAIL PROTECTED]>
Hi Phil, Got your point. I know TI doesn't have support for SD card boot. But, can I boot from the SD-Card with all UBL, U-Boot and kernel in it with the NAND flash not involved at all? I'd read some posts in the mail list that someone had come close to doing it. Thanks, Madhu On Thu, Oct 16, 2008 at 5:12 PM, Phil Quiney <[EMAIL PROTECTED] > wrote: > Hi, > > No need to use SD cards - on a DM355 there is 2G of FLASH. > > Depending on what you want the system to do this should be plenty of space > for duplicating kernel & filesystems - it is for us ;-). > > Regards > > Phil Q > > Phil Quiney, Principal Software Engineer > Trinity Convergence > Cambridge Business Park > Cowley Road > Cambridge CB4 0WZ, UK > T: +44(0)1223-435536 > F: +44(0)1223-435560 > www.trinityconvergence.com > > > ------------------------------ > *From:* [EMAIL PROTECTED] [mailto: > [EMAIL PROTECTED] *On Behalf Of *madhukesh > s > *Sent:* 16 October 2008 10:03 > *To:* [email protected] > *Subject:* Re: Davinci-linux-open-source Digest, Vol 34, Issue 56 > > > Hi Phil, > > Two copies of kernel and filesystem ? Will you be using SD MMC card for > this? > > > -----Original Message----- > > From: > > [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] > > On Behalf Of Jon Povey > > Sent: 14 October 2008 14:15 > > To: [EMAIL PROTECTED]; > > [email protected] > > Subject: RE: DM355 bootloader > > > > Phil wrote: > > > > > AFAIK 'UBL' is the U-Boot Loader - that is a > > very small program that > > > copies the U-Boot image from NAND into RAM and runs > > it. This may well > > > be an assembly language program (I have never had any > > reason to study > > > it) so good luck if you want to change it. > > > > The UBL is a TI app, I think it stands for "User Boot > > Loader" (At least on DM355). > > I have seen source for it, somewhere.. > > UBL is needed because u-boot can't load itself from > > NAND flash, and you can't do XIP. > > > > Confusing side-note: > > > > I'm a bit less sure why the RBL can't load u-boot > > directly.. I think I worked it out at some point, it's > > because the RBL can only load something that fits into one > > block, or something like that. The TI UBL is just a little > > bit of glue between RBL and u-boot, as I understand it. > > > > > U-Boot is the boot loader. It allows rudimentary > > access to the FLASH > > > and RAM on the board and typically a way of loading an > > operating > > > system kernel. Integrating an app updater into this > > may be a challenge > > > especially as it knows nothing about JFFS/YAFFS > > filesystems. You may > > > be able to FLASH the entire filesystem but that gets > > interesting if > > > the filesystem image won't fit in RAM and you have > > to know about any > > > bad blocks in the NAND as well. > > > > I am looking into how to do all this stuff on DM355 at the > > moment. My current plan is to have two copies of the kernel, > > two entirely separate filesystem partitions, and update one > > while the other is running, then switch (probably by > > changing u-boot environment variables). > > > > -- > > Jon Povey, Design Engineer > > [EMAIL PROTECTED] | +44(0)1280 825983 >
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