From: William Hermans <[email protected]> Reply-To: <[email protected]> Date: Tuesday, January 7, 2014 at 7:08 PM To: <[email protected]> Subject: Re: [beagleboard] Re: recommend usb external drive for booting?
> "So, what is the SD card? It can't just boot off the USB? I believe in this > case, I am still correct. " > > So, what is a BIOS ? If in this case you are correct, then no computer system > out there can boot off of USB. As all computer devices need to know how to > bring up the hardware, DDR memory( > now days ) , and from where to boot. > > Ok, so I was wrong, guess you do not care if someone can boot their BBB's off > of a USB drive. Hi William, Don¹t get so defensive. Gerald is a hardware guy and so you should always interpret his answers with that in mind. Anyway, if you read the AM3359 TRM, it says the following: 26.1.8.6.1 Device Initialization The ROM code supports booting from the USB interface under the following conditions: € When the high-speed USB OTG (USBOTGHS) IP is used through USB0 interface. € USB operates in full-speed, client mode. USB will operate only in device-powered mode. € Integrated transceiver (through UTMI). € The enumeration default timeout is 3s (USB timeout). € ROM code uses the default value of DATAPOLARITY. Even though using an OTG capable hardware, the ROM Code does not handle any OTG specific feature. 26.1.8.6.1.1 Overview In case of boot from USB is chosen by the SYSBOOT pin configuration: € The USBOTGHS hardware and PRCM clocks are configured for UTMI mode. € The ROM Code continues with the USB procedure only if the USB cable is detected present (i.e. VBUS is detected at transceiver level and communicated as such through the UTPI traffic). If not, the initialization procedure is aborted. € The ROM code implements the RNDIS class driver. € From a user's perspective, USB boot is indistinguishable from Ethernet boot. € The USB initialization procedure is shown in Figure 26-24 Regards, John > > > On Tue, Jan 7, 2014 at 7:56 PM, William Hermans <[email protected]> wrote: >> If you actually read the article, you would realize there is no need to >> modify anything rh_ . . . >> >> >> On Tue, Jan 7, 2014 at 7:56 PM, William Hermans <[email protected]> wrote: >>> >>> >>> On Tue, Jan 7, 2014 at 7:55 PM, William Hermans <[email protected]> wrote: >>>> Actually, its loading the kernel from the HDD. Only the uboot files need be >>>> read, so as the device knows where to boot *from*. >>>> >>>> If you want to be a 100% nitpicking techno-junkie, then a purely 100% >>>> SD/eMMC-less boot can be had by using eprom . . . as it stands, this form >>>> of USB boot satisfies me, and 99% of the other people out there :) >>>> >>>> >>>> On Tue, Jan 7, 2014 at 7:13 PM, rh_ <[email protected]> wrote: >>>>> On Tue, 7 Jan 2014 16:18:00 -0600 >>>>> Gerald Coley <[email protected]> wrote: >>>>> >>>>>> > Correct. It is actually booting form the SD and then loading off the >>>>>> > HDD. The boards cannot boot direct off of USB. They need that >>>>>> > intermediate step. You could also use a large thumb drive like a >>>>>> > 128GB. >>>>> >>>>> You are correct those instructions should be modifed to note the reliance >>>>> on >>>>> the sd card or eMMC. >>>>> >>>>> I recall that the lack of booting straight from USB was designed in >>>>> but I don't recall what the reason was. Do you know? It's common >>>>> for devices to boot from USB and I even recall reading USB was checked >>>>> during the boot process, after SPI (I think). I may have read that in the >>>>> TRM or is it SRM...? >>>>> >>>>> -- >>>>> For more options, visit http://beagleboard.org/discuss >>>>> --- >>>>> You received this message because you are subscribed to the Google Groups >>>>> "BeagleBoard" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send an >>>>> email to [email protected] >>>>> <mailto:beagleboard%[email protected]> . >>>>> For more options, visit https://groups.google.com/groups/opt_out. >>>> >>> >> > > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
