Re: [Qemu-devel] sparc hflags support?

["Blue Swirl" <blauwirbel@gmail.com>]

On 11/5/07, Robert Reif <reif@earthlink.net> wrote:
> I'm looking at adding more complete support for different sparc32
> CPUs, MMUs,  cache controllers and systems.

Great! The only problems I see are that OpenBIOS support needs to be
added for the new CPUs and supporting all CPUs with one image may
become a bit complex.

> Each CPU/MMU/cache controller combination is slightly different and
> requires its own unique state.  For example the two CPUs currently
> supported save the boot mode in different bits in the MMU control
> register: 0x2000 for the SuperSparc and 0x4000 for the TurboSparc.
> Others bits will need to be saved in the MMU and cache controllers
> as better hardware emulation is added.

I think other targets have better design for supporting different CPU
types, for example MIPS and PPC.

> It looks like other architectures handle this by computing hflags
> in the target directories but sparc determines the flags value to save
> in common code.
>
> Are there plans to add hflags support to sparc?  I'm willing work
> on it but I don't have the experience yet to tackle a job like this
> without help.

It could bring some performance benefit. Just try to move the tb flags
computation to op_helper.c. Every time hflags elements change,
recompute the flags. I'd be happy to try to help you.