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Re: [Qemu-discuss] Coldfire 5282 Support

From: Peter Maydell
Subject: Re: [Qemu-discuss] Coldfire 5282 Support
Date: Sat, 9 Sep 2017 13:30:03 +0100

On 8 September 2017 at 21:32, William Mahoney <address@hidden> wrote:
> "digic_load_rom()" knows the filename via an extern “bios_name” which is at 
> “include/sysemu/sysemu.h” but really lives in “vl.c”. It is set based on 
> “machine_ops” that comes from “qemu_get_machine_opts()” which in turn comes 
> from “emu_find_opts_singleton()” which is in "util/qemu-config.c”…
> Shortcut time. Presumably there is a way to specify some command line switch, 
> described as “-bios”, and have the filename end up at “digit_load_rom()”. But 
> I don’t see the direct path, or a header with all the options listed for the 
> specific machine, or… Can you walk me through how a “-bios” command line 
> switch is actually supposed to appear (it doesn’t on qemu-system-arm)?

This should all just work and you don't need to care about
the details of our command line parsing. (Feel free to dig
into it if you want to, but generally QEMU is big enough
that you'll make more progress if you take on trust the
parts of the code that you don't immediately need to deal
with. Nobody completely understands the entire system.
In this case what happens is that in vl.c we handle the
-bios option via the QEMU_option_bios: case in the option
processing switch by setting the value of the "firmware"
option in the "machine" options set, and then later on we
pull it back out again to set the bios_name global.)

As an ARM example, hw/arm/vexpress.c reads bios_name to
get the filename that the user specified with -bios (if any).

-- PMM

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