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 <http://www.trinityconvergence.com/>
________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of madhukesh s Sent: 16 October 2008 10:03 To: davinci-linux-open-source@linux.davincidsp.com 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]; > davinci-linux-open-source@linux.davincidsp.com > 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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