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Re: [Qemu-devel] [qemu PATCH 2/2] arm: add fw_cfg to "virt" board
From: |
Andrew Jones |
Subject: |
Re: [Qemu-devel] [qemu PATCH 2/2] arm: add fw_cfg to "virt" board |
Date: |
Fri, 28 Nov 2014 11:51:30 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Fri, Nov 28, 2014 at 11:43:32AM +0100, Laszlo Ersek wrote:
> On 11/28/14 11:38, Andrew Jones wrote:
> > On Fri, Nov 28, 2014 at 12:18:27AM +0100, Laszlo Ersek wrote:
> >> fw_cfg already supports exposure over MMIO (used in ppc/mac_newworld.c,
> >> ppc/mac_oldworld.c, sparc/sun4m.c); we can easily add it to the "virt"
> >> board.
> >>
> >> The mmio register block of fw_cfg is advertized in the device tree. As
> >> base address we pick 0x09020000, which conforms to the comment preceding
> >> "a15memmap": it falls in the miscellaneous device I/O range 128MB..256MB,
> >> and it is aligned at 64KB.
> >>
> >> fw_cfg automatically exports a number of files to the guest; for example,
> >> "bootorder" (see fw_cfg_machine_reset()).
> >>
> >> Signed-off-by: Laszlo Ersek <address@hidden>
> >> ---
> >> hw/arm/virt.c | 21 +++++++++++++++++++++
> >> 1 file changed, 21 insertions(+)
> >>
> >> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> >> index 314e55b..070bd34 100644
> >> --- a/hw/arm/virt.c
> >> +++ b/hw/arm/virt.c
> >> @@ -68,6 +68,7 @@ enum {
> >> VIRT_UART,
> >> VIRT_MMIO,
> >> VIRT_RTC,
> >> + VIRT_FW_CFG,
> >> };
> >>
> >> typedef struct MemMapEntry {
> >> @@ -107,6 +108,7 @@ static const MemMapEntry a15memmap[] = {
> >> [VIRT_GIC_CPU] = { 0x08010000, 0x00010000 },
> >> [VIRT_UART] = { 0x09000000, 0x00001000 },
> >> [VIRT_RTC] = { 0x09010000, 0x00001000 },
> >> + [VIRT_FW_CFG] = { 0x09020000, FW_CFG_SIZE + FW_CFG_DATA_SIZE },
> >> [VIRT_MMIO] = { 0x0a000000, 0x00000200 },
> >> /* ...repeating for a total of NUM_VIRTIO_TRANSPORTS, each of that
> >> size */
> >> /* 0x10000000 .. 0x40000000 reserved for PCI */
> >> @@ -519,6 +521,23 @@ static void create_flash(const VirtBoardInfo *vbi)
> >> g_free(nodename);
> >> }
> >>
> >> +static void create_fw_cfg(const VirtBoardInfo *vbi)
> >> +{
> >> + hwaddr base = vbi->memmap[VIRT_FW_CFG].base;
> >> + char *nodename;
> >> +
> >> + fw_cfg_init(0, 0, base, base + FW_CFG_SIZE);
> >> +
> >> + nodename = g_strdup_printf("/address@hidden" PRIx64, base);
> >> + qemu_fdt_add_subnode(vbi->fdt, nodename);
> >> + qemu_fdt_setprop_string(vbi->fdt, nodename,
> >> + "compatible", "fw-cfg,mmio");
> >> + qemu_fdt_setprop_sized_cells(vbi->fdt, nodename, "reg",
> >> + 2, base, 2, FW_CFG_SIZE,
> >> + 2, base + FW_CFG_SIZE, 2,
> >> FW_CFG_DATA_SIZE);
> >
> > Overkill suggestion alert, but how about defining something like
> >
> > #define FW_CFG_SIZE_ALIGNED \
> > MIN(QEMU_ALIGN_UP(FW_CFG_SIZE, FW_CFG_DATA_SIZE), \
> > QEMU_ALIGN_UP(FW_CFG_SIZE, 4))
> >
> > and then using that in your memmap size calculation and fw-cfg-data base
> > address calculation. The only reason I suggest this is because it's hard
> > to tell that fw-cfg-data's address will be naturally aligned without
> > hunting down the definition of FW_CFG_DATA_SIZE. And, if it were to change
> > (which it probably never will), then it may not be.
>
> Why does it need to be aligned?
Natural alignment is more efficient.
>
> The selector register is aligned at a 64KB boundary (for independent,
> strict reasons).
>
> The data register is not aligned at all, and -- AFAICS -- it need not
> be, because it's 1 byte wide. (In fact the ARM-specific
> Mmio(Read|Write)XX functions in edk2 enforce natural alignment, and the
> above layout passes without problems.)
Right. As FW_CFG_DATA_SIZE is currently 1 byte, it's already naturally
aligned, and the macro definition I have above actually doesn't change
anything (which is why I gave the overkill alert). However if
FW_CFG_DATA_SIZE was to change, then the natural alignment could be lost.
>
> The full register block is 3 bytes wide. Is that a problem?
No, it's fine as is, and the FW_CFG_SIZE_ALIGNED would leave it 3 bytes
wide too. FW_CFG_SIZE_ALIGNED only adds future-proofing. However it
really is overkill as the chance that FW_CFG_DATA_SIZE will change is nil.
>
> Thanks
> Laszlo
>
> >
> >> + g_free(nodename);
> >> +}
> >> +
> >> static void *machvirt_dtb(const struct arm_boot_info *binfo, int
> >> *fdt_size)
> >> {
> >> const VirtBoardInfo *board = (const VirtBoardInfo *)binfo;
> >> @@ -604,6 +623,8 @@ static void machvirt_init(MachineState *machine)
> >> */
> >> create_virtio_devices(vbi, pic);
> >>
> >> + create_fw_cfg(vbi);
> >> +
> >> vbi->bootinfo.ram_size = machine->ram_size;
> >> vbi->bootinfo.kernel_filename = machine->kernel_filename;
> >> vbi->bootinfo.kernel_cmdline = machine->kernel_cmdline;
> >> --
> >> 1.8.3.1
> >>
>
- [Qemu-devel] [qemu PATCH 0/2] DTB- and MMIO-based fw_cfg for hw/arm/virt, (continued)
- [Qemu-devel] [qemu PATCH 0/2] DTB- and MMIO-based fw_cfg for hw/arm/virt, Laszlo Ersek, 2014/11/27
- Re: [Qemu-devel] [qemu PATCH 2/2] arm: add fw_cfg to "virt" board, Andrew Jones, 2014/11/28
- Re: [Qemu-devel] [qemu PATCH 2/2] arm: add fw_cfg to "virt" board, Laszlo Ersek, 2014/11/28
- Re: [Qemu-devel] [qemu PATCH 2/2] arm: add fw_cfg to "virt" board, Laszlo Ersek, 2014/11/28
- Re: [Qemu-devel] [qemu PATCH 2/2] arm: add fw_cfg to "virt" board, Andrew Jones, 2014/11/28
- Re: [Qemu-devel] [qemu PATCH 2/2] arm: add fw_cfg to "virt" board,
Andrew Jones <=
[Qemu-devel] [edk2 PATCH 00/12] consume fw_cfg boot order in ArmVirtualizationQemu, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 01/12] ArmVirtualizationPkg: VirtFdtDxe: forward FwCfg addresses from DTB to PCDs, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 02/12] ArmVirtualizationPkg: introduce QemuFwCfgLib instance for DXE drivers, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 03/12] ArmVirtualizationPkg: clone PlatformIntelBdsLib from ArmPlatformPkg, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 04/12] ArmVirtualizationPkg: PlatformIntelBdsLib: add basic policy, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 05/12] OvmfPkg: extract QemuBootOrderLib, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 07/12] OvmfPkg: introduce VIRTIO_MMIO_TRANSPORT_GUID, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 08/12] ArmVirtualizationPkg: VirtFdtDxe: use dedicated VIRTIO_MMIO_TRANSPORT_GUID, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 09/12] OvmfPkg: QemuBootOrderLib: widen ParseUnitAddressHexList() to UINT64, Laszlo Ersek, 2014/11/27
- [Qemu-devel] [edk2 PATCH 10/12] OvmfPkg: QemuBootOrderLib: OFW-to-UEFI translation for virtio-mmio, Laszlo Ersek, 2014/11/27