Re: [Qemu-devel] [PATCH v4 4/5] acpi: arm: add fw_cfg device node to dsdt

[Gabriel L. Somlo]

On Wed, Sep 30, 2015 at 12:21:08PM +0200, Laszlo Ersek wrote:
> On 09/30/15 11:59, Ard Biesheuvel wrote:
> > On 29 September 2015 at 20:26, Gabriel L. Somlo <address@hidden> wrote:
> >> On Tue, Sep 29, 2015 at 12:40:16PM +0200, Laszlo Ersek wrote:
> >>> On 09/27/15 23:29, Gabriel L. Somlo wrote:
> >>>> Add a fw_cfg device node to the ACPI DSDT. This is mostly
> >>>> informational, as the authoritative fw_cfg MMIO region(s)
> >>>> are listed in the Device Tree. However, since we are building
> >>>> ACPI tables, we might as well be thorough while at it...
> >>>>
> >>>> Signed-off-by: Gabriel Somlo <address@hidden>
> >>>> ---
> >>>>  hw/arm/virt-acpi-build.c | 15 +++++++++++++++
> >>>>  1 file changed, 15 insertions(+)
> >>>>
> >>>> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> >>>> index 1aaff1f..f314132 100644
> >>>> --- a/hw/arm/virt-acpi-build.c
> >>>> +++ b/hw/arm/virt-acpi-build.c
> >>>> @@ -110,6 +110,20 @@ static void acpi_dsdt_add_rtc(Aml *scope, const 
> >>>> MemMapEntry *rtc_memmap,
> >>>>      aml_append(scope, dev);
> >>>>  }
> >>>>
> >>>> +static void acpi_dsdt_add_fw_cfg(Aml *scope, const MemMapEntry 
> >>>> *fw_cfg_memmap)
> >>>> +{
> >>>> +    Aml *dev = aml_device("FWCF");
> >>>> +    aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
> >>>> +    /* device present, functioning, decoding, not shown in UI */
> >>>> +    aml_append(dev, aml_name_decl("_STA", aml_int(0xB)));
> >>>> +
> >>>> +    Aml *crs = aml_resource_template();
> >>>> +    aml_append(crs, aml_memory32_fixed(fw_cfg_memmap->base,
> >>>> +                                       fw_cfg_memmap->size, 
> >>>> AML_READ_WRITE));
> >>>> +    aml_append(dev, aml_name_decl("_CRS", crs));
> >>>> +    aml_append(scope, dev);
> >>>> +}
> >>>> +
> >>>>  static void acpi_dsdt_add_flash(Aml *scope, const MemMapEntry 
> >>>> *flash_memmap)
> >>>>  {
> >>>>      Aml *dev, *crs;
> >>>> @@ -529,6 +543,7 @@ build_dsdt(GArray *table_data, GArray *linker, 
> >>>> VirtGuestInfo *guest_info)
> >>>>                         (irqmap[VIRT_UART] + ARM_SPI_BASE));
> >>>>      acpi_dsdt_add_rtc(scope, &memmap[VIRT_RTC],
> >>>>                        (irqmap[VIRT_RTC] + ARM_SPI_BASE));
> >>>> +    acpi_dsdt_add_fw_cfg(scope, &memmap[VIRT_FW_CFG]);
> >>>>      acpi_dsdt_add_flash(scope, &memmap[VIRT_FLASH]);
> >>>>      acpi_dsdt_add_virtio(scope, &memmap[VIRT_MMIO],
> >>>>                      (irqmap[VIRT_MMIO] + ARM_SPI_BASE), 
> >>>> NUM_VIRTIO_TRANSPORTS);
> >>>>
> >>>
> >>> Looks sane to me.
> >>>
> >>> Did you test this with an aarch64 Linux guest (acpidump -b; iasl -d; cat
> >>> /proc/iomem?) I can help with that, if you'd like.
> >>
> >> I have a F22 arm setup generated by virt-builder, which I start using:
> >>
> >> bin/qemu-system-arm -M virt,accel=tcg -cpu cortex-a15 \
> >>   -kernel ./ArmVirtBuilder/vmlinuz-4.0.4-301.fc22.armv7hl+lpae \
> >>   -initrd ./ArmVirtBuilder/initramfs-4.0.4-301.fc22.armv7hl+lpae.img \
> >>   -append "console=ttyAMA0 root=/dev/vda3 ro" \
> >>   -device virtio-blk-device,drive=hd0 \
> >>   -drive id=hd0,if=none,snapshot=on,file=./ArmVirtBuilder/fedora-22.img \
> >>   -device virtio-net-device,netdev=usernet \
> >>   -netdev user,id=usernet \
> >>   -monitor stdio
> >>
> > 
> > Note that you are booting 32-bit ARM here, which does not support ACPI nor 
> > UEFI.
> > (UEFI is work in progress, so you can try my ARM 32-bit UEFI tree if
> > you need to: 
> > https://git.linaro.org/people/ard.biesheuvel/linux-arm.git/shortlog/refs/heads/arm-efi-combined-v2)

I'm noticing that even on 32-bit arm there are ACPI tables generated and
inserted into fw_cfg, so is there any reason OTHER than lack of firmware
support for ACPI not being supported on 32-bit arm ?

> > You will need to create an arm64 / AArch64 setup and boot the virt
> > model using 'qemu-system-aarch64 -M virt -cpu cortex-a57 ...' instead.
> > In either case, as Laszlo pointed out, you need UEFI firmware in QEMU
> > as well.
> 
> I'm about to follow up with my test results, and I considered writing up
> a more or less complete guide for Gabriel to test this with an aarch64
> guest.
> 
> However: if Gabriel has no access to actual aarch64 hardware (ie. cannot
> run KVM guests), then I don't think he should bother. Booting just the
> UEFI firmware on qemu-system-aarch64 with TCG acceleration is fine, but
> for checking "/proc/iomem", he'd really need to boot into guest Linux,
> and *that* takes absolutely forever with TCG.
> 
> (Dependent on your guest distro, of course; I have tested Fedora 21+ and
> RHELSA / RHEL-7 candidates thus far. I wouldn't recommend TCG for those.)
> 
> So, I'll just leave these links here for posterity (they could be
> somewhat outdated), and I offer to help with aarch64 guest testing in
> the future as well, if the patch series overlaps with my interests.
> 
> https://wiki.linaro.org/LEG/UEFIforQEMU
> https://fedoraproject.org/wiki/Architectures/AArch64/Install_with_QEMU

Thanks to both of you for the pointers, I will probably invest some
time in getting set up with UEFI firmware for my arm guests at some
point, when the dust settles on all the other fun :)

Thanks,
--Gabriel