[SeaBIOS] [PATCH 1/3] Add generic qemu detection
Kevin O'Connor
kevin at koconnor.net
Wed Sep 4 03:28:08 CEST 2013
On Tue, Sep 03, 2013 at 02:37:41PM +0200, Gerd Hoffmann wrote:
> This patch adds support for detecting whenever SeaBIOS runs on qemu
> or not. This is done by looking at the northbridge (pci device 00:00.0)
> and check the subsystem id. Most pci devices emulated by qemu -- the
> two northbridges i440fx and q35 included -- have a subsystem id of
> "1af4:1100".
In general, it looks sane to me. It does mix the "preinit" phase (on
coreboot/qemu) with the "init" phase (on csm). Can the detect just be
done in qemu_cfg_init (perhaps renaming it to qemu_init) and that way
this detection doesn't need to be done in the preinit phase.
> --- a/src/paravirt.c
> +++ b/src/paravirt.c
> @@ -19,6 +19,7 @@
> #include "acpi.h" // acpi_setup
> #include "mptable.h" // mptable_setup
> #include "pci.h" // create_pirtable
> +#include "pci_regs.h" // create_pirtable
> #include "xen.h" // xen_biostable_setup
>
> // Amount of continuous ram under 4Gig
> @@ -33,10 +34,8 @@ int PlatformRunningOn VARFSEG;
> */
> #define KVM_CPUID_SIGNATURE 0x40000000
>
> -static void kvm_preinit(void)
> +static void kvm_detect(void)
> {
> - if (!CONFIG_QEMU)
> - return;
> unsigned int eax, ebx, ecx, edx;
> char signature[13];
>
> @@ -52,9 +51,43 @@ static void kvm_preinit(void)
> }
> }
>
> +void qemu_detect(void)
> +{
> + if (!CONFIG_QEMU_HARDWARE)
> + return;
> +
> + // check northbridge @ 00:00.0
> + u16 v = pci_config_readw(0, PCI_VENDOR_ID);
> + if (v == 0x0000 || v == 0xffff)
> + return;
> + u16 d = pci_config_readw(0, PCI_DEVICE_ID);
> + u16 sv = pci_config_readw(0, PCI_SUBSYSTEM_VENDOR_ID);
> + u16 sd = pci_config_readw(0, PCI_SUBSYSTEM_ID);
> +
> + if (sv != 0x1af4 || /* Red Hat, Inc */
> + sd != 0x1100) /* Qemu virtual machine */
> + return;
> +
> + PlatformRunningOn |= PF_QEMU;
Do old versions of QEMU set this also? (If not, there is a corner
case where we could have CONFIG_QEMU but PlatformRunningOn != PF_QEMU
- I don't think that matters, but it is weird.)
-Kevin
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