[Qemu-devel] Re: [PATCH] Seabios irq override v3

[Beth Kon <eak@us.ibm.com>]

Jes Sorensen wrote:
> On 07/30/2009 01:27 AM, Kevin O'Connor wrote:
>> I made some cleanups and committed a modified patch.
>>
>> I'd like to see what the dynamic irq0override code looks like.  The
>> kvm on my machine is a little older and it fails when irq0override is
>> set.
>>
>> Also, there is a set of irq overrides in the acpi madt code for kvm
>> that set irq 5,9,10,11 to level triggered interrupts.  I don't see
>> this in the latest kvm - can this now be removed?
>
> Hi Kevin,
>
> I justed tested your version and it works fine here. If I got some of
> the formatting wrong, please let me know and I'll try to get it right
> in the next set.
>
> The tricky part with the irqoverride is that it is used by recent KVM,
> but not older versions. qemu-kvm has a fw_cfg flag it uses to set (and
> not set it when it detects an older version of KVM), however upstream
> QEMU relies on the irqoverride unconditionally.
>
> As the BIOS cannot detect which version of KVM it is running on, there
> are two options, either we port the irqoverride fw_cfg to upstream QEMU,
> or accept that Seabios will not work on older versions of KVM. I don't
> think Anthony is super excited about adding this to upstream QEMU since
> it is for legacy support, and I don't anticipate any distros starting
> to ship Seabios with older version of KVM. I think it would be simpler
> to just accept it won't work with the older KVM.
>
> I thought about how to best do the dynamic override thing, and I think
> the best thing is to just set it when we detect we are running on QEMU,
> be it QEMU, KVM, or KQEMU. I have a patch that allows me to remove all
> instances of CONFIG_KVM in Seabios, by using a new fw_cfg that tells the
> bios what emulator it is running on. It would be interesting to see if
> we could come up with a way for Coreboot to flag as well, so we can
> share a single BIOS binary.
>
> For the MADT stuff, I really don't know. Maybe Avi or Anthony can
> comment?
 if (PCI_ISA_IRQ_MASK & (1U << i)) {
                memset(int_override, 0, sizeof(*int_override));
                int_override->type   = APIC_XRUPT_OVERRIDE;
                int_override->length = sizeof(*int_override);
                int_override->source = i;
                int_override->gsi    = i;
                int_override->flags  = 0xd; /* active high, level 
triggered */
            } else {

The above code is still in qemu-kvm/kvm/bios/rombios32.c, but has never 
been in qemu/bochs bios. I don't understand why.

In any case it has nothing to do with the irq0override code.












 is still in the latest kvm bios but has never been in the qemu/bochs 
bios. I don't understand why that is.
>
> I will post this patch shortly, I just need to make a few more minor
> tweaks to it.
>
> Cheers,
> Jes