Hi, Aras Vaichas : > Hi, > > we're designing our next generation RFID reader and I'm planning on > using the AT91SAM9G20 in the next design. We currently use the > AT91RM9200. Good choice ;-) > Can I get some feedback from people with regards to general design > configurations that affect the boot time with respect to this CPU (or > the AT91SAM9260) I presume that you already know what are the configurations we are using at Linux4sam.org on our at91sam9g20ek board. Anyway, I answer your questions as it may also interest other readers. > Some questions are: > > * what is your boot time? What is the time from power-on to kernel > running, how long does the kernel take to run until init starts, and > how long does init take? We have not tried to be clever on speeding up boot process but I guess that we can save time: - removing unneeded bootloader steps (remove u-boot for instance) - removing unused drivers - lower timeouts (Ethernet phy detection for example) - tailor rootfs exactly to your needs That said, here are numbers from our not optimized demo (AT91Bootstrap+u-boot+linux+buildroot): - ~6s to Linux (can certainly be optimized) - ~+2s to init - ~+5s to login (here also) > * what is your system hardware configuration? CPU+NAND, CPU+NOR+NAND, > CPU+DATAFLASH+NAND? CPU + NAND can lower your BOM > * do you boot everything from the NAND or do you use a combination of > Dataflash/NOR and NAND? Both. > * do you use U-Boot, or a minimal custom bootloader that copies a > kernel image from NAND to SDRAM and then executes it? If boot time is a hot topic, choose AT91Bootstrap that directly loads Linux. > * do you mount a small partition of the NAND to begin with and then > mount the rest later? With JFFS2, I advice you to tailor your NAND partition for rootfs to the minimum. You will then have room in another partition once your system is up-n-running. > * do you have a monolithic kernel, or is it split into minimal with > modules loaded from, say, JFFS2 on NAND? Monolithic kernel. > * are you using JFFS2 or UBIFS? JFFS2 for the moment. We will certainly consider moving to UBIFS. Bye, -- Nicolas Ferre -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
