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 <ler...@redhat.com> >> --- >> 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("/fw-cfg@%" 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? 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.) The full register block is 3 bytes wide. Is that a problem? 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 >>