From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Edwards Date: Tue, 23 Feb 2010 23:32:21 +0000 (UTC) Subject: [Buildroot] Newbie: AT91SAM9260 NAND Boot References: <815f0bd71002221951v606dbdddn381587fdd662e485@mail.gmail.com> <815f0bd71002231515m11ed502bxa3268af876dcdafb@mail.gmail.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net On Wed, Feb 24, 2010 at 10:15:18AM +1100, Roo wrote: >>> I am new to buildroot and have been given a AT91SAM9260 SOM to >>> work with. The latest buildroot does not appear to include a >>> defconfig for a NAND boot system. >> >> Can you explain what a "NAND boot system" is? >> >> When I boot an AT91SAM9xxx from NAND, I tell buildroot to >> build a JFFS2 root image, a uImage kernel with MTD/JFFS2 >> support, put the resulting kernel and root image into NAND, >> and configure U-Boot to boot from NAND. > > I believe that I had some of the terminology wrong. > > I would like a jffs (or a readonly FS) to reside in NAND as > you had described, but I was confused by the > dataflash/dataflashcard terminology. I thought it was > referring to a SD or micro SD card and I do not want the > rootfs or kernel to reside on the card. Dataflash is a serial NOR-flash part that's attached to an SPI interface. It's sort of similar to an SD-card, but the interface/protocol is a little different. > My understanding now is that configurations relate to where > the bootloader resides rather than where the rootfs resides. I > am little embarrassed that I didn't realise this earlier and > if I am right this just got easier. :) You're probably right. Buildroot can build U-Boot and, IIRC, also the low-level SAM9 bootloader: it's what is initially loaded by the MCU's built-in bootloader from somewhere (NAND, NOR, SDcard, dataflash) into internal SRAM and run -- it enables SDRAM, and then loads U-Boot from somewhere (same choices as before) into SDRAM, and then runs U-Boot. U-Boot then loads a kernel image into SDRAM (and optionally loads a rootfs into SDRAM), and boots the kernel. And there's no rule that says the low-level SAM9 bootloader, U-Boot, the kernel, and the rootfs can't all be on different media. I've never selected either the bootloader or U-Boot in buildroot, so I don't know what configuration options are available for them -- but I would guess that support for the various boot media are configurable. -- Grant Edwards grante Yow! World War III? at No thanks! visi.com