The platform I started with was ppc_prep :-)
So, is Python already part of qemu? Personally, I would have a goal
that the definition of a device would be simple enough that there
would be no reason to have anything more complicated than a simple
text file. While I would not suggest that the BSD config file syntax
should be used, I do think it is instructive.
It has a section for defining macros, really, the standard name/value
pairs
options KTR # kernel wraparound trace
buffer support
options "KTR_SIZE=32768" # trace buffer in bytes (def=8K)
options "KTR_COMPILE='~0'" # compile in all traces
options "KTR_MASK=0" # but turn none of them on
Clearly there would be cleaner ways to specify this for QEmu
set memory_size 0x10000000
There is also a section that specifies the various devices. Here is
a snippet of a kernel for an embedded PPC board I used to work on:
# main (on-board io) bus
obio0 at root
pci0 at obio0
# COM ports
# Flags are 0xF00000 for fifo flags F; see com(4).
# Default is 0; 1, 2, 3, 4 set receive fifo trigger to 1, 4, 8, 14;
# 9 ignores the FIFO on 16550/16550AF.
com0 at obio? addr "0xff600300" irq 3
com1 at obio? addr "0xff600400" irq 4
# Crystal Semiconductor Ethernet
ce0 at obio? addr "0x7fe00c00" irq 24
# Disk On Chip 2000 driver
dc0 at obio? iomem "0x800d0000" iosiz 0x2000
This particular syntax specifies several things:
1) The devices in a generic way
2) How devices are connected
3) The order to search for the devices
Again, QEmu would need something slightly different, but at least
this demonstrates how a similar problem has been previous solved.
There are also pseudo devices
pseudo-device loop
pseudo-device pty
pseudo-device sl 1
QEmu might be able to treat pseudo and "physical" devices the same,
or maybe keeping them independent would be good.
Using python, or some general purpose scripting language, to
create .c files for inclusion in the compilation seems like it may
have some merit, though I see these as different issues. I wrote a
PPC virtual machine to run on PPC hosts (i.e., more like vmware).
When I found that I wanted a little more than a simple ascii file, I
settled on pretty much the standard sh syntax. I have written (and
am willing to contribute) an embedded version of sh which only calls
builtin functions. I used it both for my monitor as well as my
config syntax (config files were essentially read by the monitor)
-Paul
Personally though I don't see much benefit to simple syntax config
files over C files, that are being used now.
Really? Take a look at ppc_prep_init()...
I would love to see machine definition done in python.
--
Hollis Blanchard
IBM Linux Technology Center
