Re: Fwd: decent reasonably-priced armhf system with sata, gigabit ethernet, dual-core processor and 2gb of RAM

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On Sat, Oct 19, 2013 at 7:45 PM, Richard W.M. Jones <rjones@xxxxxxxxxx> wrote:

> I'm currently testing the ODROID-XU.

 i got the odroid-u2.  installation report here:
 http://lkcl.net/reports/odroid-u2.html

 yes, there is no buffer on the RS232 port.  you *really* have to
watch out.  henrik (hno) knows the full technical details, but
basically TTL "off" (0) on UART is 3.3V (opposite of what you think it
might be).  so when you power down, the USB-to-RS232 converter is
basically providing random 3.3V power *into* the processor.  This Is
Generally Bad.

henrik knows how to sort this out (resistors, diode) but basically *do
not* have the USB-to-RS232 converter plugged in when the power is off.
 if you want to get at the boot sequence, then either a) tough b) get
in there quick and repeat until success! :)

i had no problems, concerns or issues about either a) the use of
micro-hdmi.  just get a cable.  b) the sd/mmc.  i got 2.  1 is an 8gb
eMMC, the other was a micro-sd converter so i could plug in a standard
micro-sd card.  the 8gb eMMC was lightning-quick.

what did i do with it?  i installed xrdp and then ran *five*
simultaneous desktop sessions on it.  6 made it keel over because i
hadn't set up any swap space (and you shouldn't really set up swap
onto an MMC card unless you expect to replace it regularly).

so yeah basically the exynos 44xx series absolutely rocks.  it's a
Cortex A9 though so no virtualisation, but with xrdp being successful
i genuinely didn't care.  if you want a Cortex A15, go for an
arndaleboard.  you'll get really good performance and virtualisation.

but, price-performance wise they're all completely outclassed by an
A20.  don't expect speed miracles compared to an A15 or an A9, but the
interfaces (SATA, Gig-Eth) and the 2gb RAM more than make up for the
"lowly" dual-core A7 aspect.

btw: exynos processors have treacherous-zone capabilities and on-board
secret-boot flash.  unfortunately all the suppliers of exynos boards
activate it, thus banning you from replacing the bootloader and often
banning you from replacing u-boot as well.  by contrast allwinner
processors are "unbrickable".  pull a pin high and you go straight
into USB "loader" mode.  which has been reverse-engineered and
software-libre (GPLv3+) sources are available for command-line
bootstrapping with a [GPL-compliant, community-managed and publicly
available] modified u-boot.

l.
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