Re: [Qemu-devel] [PATCH v3] Add DSDT node for AppleSMC

[Laszlo Ersek <lersek@redhat.com>]

On 12/22/13 18:14, Gabriel L. Somlo wrote:
> On Sun, Dec 22, 2013 at 04:58:58PM +0100, Laszlo Ersek wrote:
>> After this patch, ISA interrupt 6 is used by both "SMC" and "FDC0". The
>> latter depends on the FDEN object, but FDEN is currently constant 1.
>>
>> Probably not a problem in practice (ie. most users won't try to specify
>> both a floppy disk controller and an AppleSMC device), but you might
>> want to handle that case nonetheless (exit with an error or some such).
> 
> I couldn't find a command line option to prevent QEMU from starting
> with a floppy controller, so unless I missed it, we'd always detect
> a "conflict".
> 
> According to the applesmc.c source, the emulated Apple SMC doesn't
> support IRQ, so the number itself should be irrelevant. IRQ #6 is
> what's used on real Apple hardware, but when I tried with a different
> number (e.g. #5), OS X booted fine in QEMU (it does fail to boot if
> we leave out IRQNoFlags entirely from the SMC DSDT node, though).
> 
> I could patch the value of FDEN to 0 whenever I enable the SMC _STA
> method (i.e, when I patch its value to 0x0B), but that still wouldn't
> take care of the fact that the emulated FDC is still present.
> 
> So, my preferred course of action would be, in this order:
> 
> 	1. Do nothing :)
> 
> or
> 
> 	2. Use "IRQNoFlags() { 5 }" with the SMC (or any other
> 	   number that isn't already allocated.

I don't think there's anything left free:

 0 - system timer (not listed explicitly)
 1 - KBD (PNP0303)
 2 - cascade / PIC (PNP0000) (listed only in OVMF's builtin DSDT)
 3 - COM2 (PNP0501)
 4 - COM1 (PNP0501)
 5 - LNK[ABCD] (PNP0C0F)
 6 - FDC0 (PNP0700)
 7 - LPT (PNP0400)
 8 - RTC (PNP0B00)
 9 - LNKS (PNP0C0F)
10 - LNK[ABCD] (PNP0C0F)
11 - LNK[ABCD] (PNP0C0F)
12 - MOU (PNP0F13)
13 - FPU (PNP0C04) (listed only in OVMF's builtin DSDT)
14 - primary IDE (not listed explicitly)
15 - secondary IDE (not listed explicitly)

See also

http://www.plasma-online.de/english/identify/serial/pnp_id_pnp.html
http://www.webopedia.com/quick_ref/IRQnumbers.asp

You could reuse eg. #5, but then you'd have to distribute PCI LNK[ABCD]
over #10 and #11 only, which I guess is too high a price (both
patch-wise and at runtime). Rather don't touch that :)

> Any other suggestions or ideas would be welcome !

I guess the "by the book" solution would be to really stop the FDC from
being emulated when the AppleSMC is present, but I mention that idea
only because I like to waste bandwidth.

Option 1 ("Do nothing") sounds appropriate to me. Sorry for taking up
some of your time...

Thanks,
Laszlo