Re: [Qemu-devel] qemu alpha?

[Oliver Falk <oliver@linux-kernel.at>]

On 10/21/2007 01:06 PM, J. Mayer wrote:
> On Sun, 2007-10-21 at 05:43 -0500, Rob Landley wrote:
>> On Saturday 20 October 2007 3:56:12 am J. Mayer wrote:
>>> On Fri, 2007-10-19 at 19:49 -0500, Rob Landley wrote:
>>>> On Sunday 14 October 2007 5:14:27 am J. Mayer wrote:
>>>>> On Sun, 2007-10-14 at 11:19 +0200, Oliver Falk wrote:
>>>>>> Hi list!
>>>>> Hi you !
>>>>>
>>>>>> Just wanted to know how far the progress on alpha target is? I would
>>>>>> be happy if I have some 'virtual alpha' to test new isos.
>>>>>>
>>>>>> If I can help some way (I have a few alphas around). Let me know.
>>>>> I'm happy to see someone interresting in improving Alpha support, which
>>>>> is .... very alpha for now !
>>>> I'm interested in testing Alpha too, but I haven't seem a
>>>> qemu-system-alpha show up yet.  Alas, I have no hardware or specific
>>>> expertise in this platform, I'm just trying to build and boot Linux
>>>> kernels (and corresponding root filesystems) on as many emulated target
>>>> platforms as I can.
>>> There are a lot of things missing for qemu-system-alpha to be available:
>>> - the PALCode emulation is far from being complete or even usable
>> I have no idea what that is.
> 
> The PALCode is mainly equivalent to the microcode of most CPU
> architectures. What is different to microcode is that is uses only
> regular Alpha instructions, just adding 4 instructions to access special
> "hardware registers" and access the memory with different priviledge
> levels. Another main idea is that everyone can write its own PALCode
> image and switch to it at run-time. Then, for example, the PALCode ABI
> is not the same one if you run Linux or Windows NT. The PALCode handles
> all complex operations. For example, the CPU provides only TLB and the
> MMU tables search is actually implemented in software, in the PALCode.
> This greatly simplifies the CPU design and allows a high level of
> flexibility. And if your OS need a specific ABI for example to handle
> CPU exception, you define your ABI, write the PALCode using Alpha insns
> and use it ! The Alpha CPU also provide an instruction to do PALCode
> calls from the OS or applications.
> There are 3 (4 ?) "native" PALCode ABIs documented in the Alpha CPUs
> specifications then those can be emulated at the host side in Qemu. It
> is in fact needed to emulate a subset of the PALCode even to run
> user-mode programs.

Pretty good explained! Thanks!



However, what do you need to make the alpha emulation work? Does ssh to
an Alpha help you? I'm quite sure I can offer you access to some ev5
machine very soon and I might give access to some ds10 (ev67 machine).
There's also some ds10 (ev6 'only') machine in Australia, that actually
works as a builder for the AlphaCore project - but it's not mine and I
would need to ask if I can give access to someone else...

-of