About FreeBSD support one more mini-pc

[Ian Lepore]

On Wed, 2014-02-19 at 16:12 -0700, Ian Lepore wrote:
> On Wed, 2014-02-19 at 15:12 -0700, Tom Everett wrote:
> > Hey Ian, i am just about to ask for a pull from my repo with a working
> > ubldr for wandboard, if you wanted to take a look:
> > 
> > https://github.com/teverett/crochet-freebsd/commit/f61660c4134ef495cb5f7de26c2048fba1e65c8f
> > 
> 
> My problem isn't with u-boot, it's in the ubldr->kernel handoff.  I'm
> using u-boot-2014.01 these days and it needs no patching other than to
> the wandboard config.h to turn on API and USB and a few other handy
> things.  But when I boot, sometimes it works but more often it goes like
> this:
>         
>         U-Boot 2014.01 (Feb 19 2014 - 15:31:16)
>         
>         CPU:   Freescale i.MX6Q rev1.2 at 792 MHz
>         Reset cause: POR
>         Board: Wandboard
>         DRAM:  2 GiB
>         MMC:   FSL_SDHC: 0, FSL_SDHC: 1
>         In:    serial
>         Out:   serial
>         Err:   serial
>         Net:   FEC
>         Hit any key to stop autoboot:  0 
>         FEC Waiting for PHY auto negotiation to complete... done
>         BOOTP broadcast 1
>         *** Unhandled DHCP Option in OFFER/ACK: 69
>         ...
>         *** Unhandled DHCP Option in OFFER/ACK: 42
>         DHCP client bound to address 172.22.42.236
>         Using FEC device
>         TFTP from server 172.22.42.240; our IP address is 172.22.42.236
>         Filename '/wand/boot/ubldr'.
>         Load address: 0x11000000
>         Loading: ##############
>                  10.4 MiB/s
>         done
>         Bytes transferred = 195484 (2fb9c hex)
>         ## Starting application at 0x11000054 ...
>         Consoles: U-Boot console  
>         Compatible API signature found @8f564028
>         Number of U-Boot devices: 2
>         
>         FreeBSD/armv6 U-Boot loader, Revision 1.2
>         (ilepore at revolution.hippie.lan, Wed Feb 19 15:41:25 MST 2014)
>         DRAM:    2048MB
>         
>         Device: disk
>         -
>         /boot/kernel/kernel text=0x42f3d0 data=0x31d14+0x2df1c syms=[0x4+0x923b0+0x4+0x6e34d]
>         Hit [Enter] to boot immediately, or any other key for command prompt.
>         Booting [/boot/kernel/kernel]...               
>         Using DTB compiled into kernel.
>         Kernel entry at 0x12000100...
>         Kernel args: (null)
>         a
> 
> And it hangs there forever.  The 'a' I just added, that shows me that it
> gets into the kernel, I print that 'a' from the first few instructions
> of locore.S.

Follow up on this... it is because I'm using a newer u-boot that has the
dcache enabled by default.  If I use the "dcache off" command to disable
it, it boots perfectly every time.  If I leave the cache enabled it
fails to boot most of the time with symptoms that pretty much exactly
match stale data in the caches.

We enable the MMU in locore.S without invalidating old cache contents
first, and that appears to be a bad thing.

-- Ian