don.bailey@gmail.com:
> So to get this back on the track of RPI emulated in QEMU … has anyone successfully used the Miller image with Q?
After a bit of experimentation, I have done so, for some value of "successfully".
A few tweaks are required first, because QEMU's emulation of Pi hardware and
firmware is not as faithful as it might be:
- binary kernel file is loaded at 0x10000, not 0x8000
- the watchdog timer doesn't work (or isn't there)
- system timer behaviour is a bit peculiar
- emulation of the SDMMC in multi-block mode is spectacularly slow
(transfers take not milliseconds but seconds)
After tweaking as shown below, a QEMU-compatible kernel can be built with
mk CONF'='pi2 9pi2.qemu
and run with something like
qemu-system-arm -M raspi2b -kernel 9pi2.qemu -serial stdio \
-drive file=9pi.img,if=sd,format=raw \
-append 'readparts=1 console=1 *ncpu=1 nobootprompt=local!/dev/sdM0/fossil'
For convenience I've put a kernel file on /n/sources/contrib/miller/9pi2.qemu
However ...
- the DWC usb host adapter of the Pi2/3 does not work the way Plan 9 expects
- therefore there's no functioning usb
- therefore I don't know how to attach a keyboard, mouse or network interface
If anybody wants to debug this further I'm happy to collaborate, but I'm
not sufficiently motivated to do it myself.
Diffs against files in /n/sources/contrib/miller/9/bcm, which I think are
identical to 9legacy 9/bcm sources):
mkfile:
85a86,90
> $p$CONF.qemu:DQ: $CONF.$O $OBJ $LIB
> $CC $CFLAGS '-DKERNDATE='`{date -n} $CONF.c
> echo '# linking kernel for QEMU'
> $LD -s -l -o $target -H6 -R4096 -T0x80010000 $OBJ $CONF.$O $LIB
>
mem.h:
48c48
< #define KTZERO (KZERO+0x8000) /* kernel text start */
---
> #define KTZERO (KZERO+0x10000) /* kernel text start */
archbcm2.c:
225c225
< addclock0link(wdogfeed, HZ);
---
> //addclock0link(wdogfeed, 1000);
sdmmc.c:
25c25
< Multiblock = 1,
---
> Multiblock = 0,
clock.c:
35c35
< MinPeriod = 10,
---
> MinPeriod = 100,
124c124
< u32int t0, t1, tstart, tend;
---
> u32int t0, t1, tstart;
142d141
< tend = tstart + 10000;
145c144
< }while(tn->clo != tend);
---
> }while(tn->clo - tstart < 10000);
------------------------------------------
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