qfw command

Synopsis

qfw dump
qfw list
qfw cpus
qfw load [kernel_addr [initrd_addr]]
qfw table
qfw arch
qfw read <addr> <filename>
qfw e820

Description

The qfw command is used to retrieve information from the QEMU firmware.

The qfw list sub-command displays the QEMU firmware files.

The qfw dump sub-command displays the QEMU configuration entries.

The qfw cpus sub-command displays the available CPUs.

The qfw load command is used to load a kernel and an initial RAM disk.

The qfw table command shows the instructions U-Boot uses to construct the ACPI tables. This is not as simple as a single blob of data, since some entries must be updated to take account of the address to which the tables are copied.

The qfw arch command shows some items marked as ‘arch local’ in QEMU.

The qfw read command allowing a QEMU file to be read into memory.

The qfw e820 command shows the memory-map information provided by QEMU. It uses the x86 e820 format.

kernel_addr: address to which the file specified by the -kernel parameter of QEMU shall be loaded. Defaults to environment variable loadaddr and further to the value of CONFIG_SYS_LOAD_ADDR.
initrd_addr: address to which the file specified by the -initrd parameter of QEMU shall be loaded. Defaults to environment variable ramdiskaddr and further to the value of CFG_RAMDISK_ADDR.
addr: address to which filename is read into memory
filename: filename of file to read into memory (as shown by qfw list)

Examples

QEMU firmware files are listed via the qfw list command:

=> qfw list
Addr     Size Sel Name
-------- -------- --- ------------
       0        0  20 bios-geometry
       0        0  21 bootorder
1fc6c000       14  22 etc/acpi/rsdp
1fc6c040    20000  23 etc/acpi/tables
       0        4  24 etc/boot-fail-wait
       0       28  25 etc/e820
       0        8  26 etc/msr_feature_control
       0       18  27 etc/smbios/smbios-anchor
       0      151  28 etc/smbios/smbios-tables
       0        6  29 etc/system-states
       0     1000  2a etc/table-loader
       0        0  2b etc/tpm/log
       0     2400  2c genroms/kvmvapic.bin

Where an address is shown, it indicates where the data is available for inspection, e.g. using the md command.

This shows the qfw dump command on an x86 target:

::: signature = QEMU id = 0x00000003 uuid = dc8275a0-59c6-11f0-b383-0f1ea10dd2f7 ram_size = 0x0000000020000000 nographic = 0x00000000 nb cpus = 0x00000004 machine id = 0x00000000 kernel addr = 0x00100000 kernel size = 0x00e9e988 kernel cmdl = 0x00000000 initrd addr = 0x1b446000 initrd size = 0x04b91d57 boot device = 0x00000000 numa = 0x00000000 boot menu = 0x00000000 max cpus = 0x00000004 kernel entry= 0x00000000 cmdline addr= 0x00020000 cmdline size= 0x0000000f cmdline data= root=/dev/sda1 setup addr = 0x00010000 setup size = 0x00005000 file dir le = 0x0000000d

The available CPUs can be shown via the qfw cpus command:

=> qfw cpu
2 cpu(s) online

The -kernel and -initrd parameters allow to specify a kernel and an initial RAM disk for QEMU:

$ qemu-system-x86_64 -machine pc-i440fx-2.5 -bios u-boot.rom -m 1G \
    -nographic -kernel vmlinuz -initrd initrd

Now the kernel and the initial RAM disk can be loaded to the U-Boot memory via the qfw load command and booted thereafter.

=> qfw load ${kernel_addr_r} ${ramdisk_addr_r}
loading kernel to address 0000000001000000 size 5048f0 initrd 0000000004000000 size 3c94891
=> zboot 1000000 5048f0 4000000 3c94891
Valid Boot Flag
Magic signature found
Linux kernel version 4.19.0-14-amd64 (debian-kernel@lists.debian.org) #1 SMP Debian 4.19.171-2 (2021-01-30)
Building boot_params at 0x00090000
Loading bzImage at address 100000 (5260160 bytes)

This shows the qfw table command on an x86 target:

=> qfw table
alloc: align 10 zone fseg name 'etc/acpi/rsdp'
alloc: align 40 zone high name 'etc/acpi/tables'
add-chksum offset 49 start 40 length 1ab4 name 'etc/acpi/tables'
add-ptr offset 1b18 size 4 dest 'etc/acpi/tables' src 'etc/acpi/tables'
add-ptr offset 1b1c size 4 dest 'etc/acpi/tables' src 'etc/acpi/tables'
add-chksum offset 1afd start 1af4 length 74 name 'etc/acpi/tables'
add-chksum offset 1b71 start 1b68 length 78 name 'etc/acpi/tables'
add-chksum offset 1be9 start 1be0 length 38 name 'etc/acpi/tables'
add-chksum offset 1c21 start 1c18 length 28 name 'etc/acpi/tables'
add-ptr offset 1c64 size 4 dest 'etc/acpi/tables' src 'etc/acpi/tables'
add-ptr offset 1c68 size 4 dest 'etc/acpi/tables' src 'etc/acpi/tables'
add-ptr offset 1c6c size 4 dest 'etc/acpi/tables' src 'etc/acpi/tables'
add-ptr offset 1c70 size 4 dest 'etc/acpi/tables' src 'etc/acpi/tables'
add-chksum offset 1c49 start 1c40 length 34 name 'etc/acpi/tables'
add-ptr offset 10 size 4 dest 'etc/acpi/rsdp' src 'etc/acpi/tables'
add-chksum offset 8 start 0 length 14 name 'etc/acpi/rsdp'

This shows the qfw table command on an x86 target:

=> qfw arch
acpi tables = 0x00000000
smbios entrs= 0x00000000
irq0 overr  = 0x00000001
hpet        = 0x00000000

This shows reading a named qfw file into memory then dumping it, using the provided size information:

=> qfw list
    Addr     Size Sel Name
-------- -------- --- ------------
       0        0  20 bios-geometry
       0        0  21 bootorder
1ec3f000       14  22 etc/acpi/rsdp
1ec3f040    20000  23 etc/acpi/tables
       0        4  24 etc/boot-fail-wait
       0       28  25 etc/e820
       0       18  26 etc/smbios/smbios-anchor
       0      151  27 etc/smbios/smbios-tables
       0        6  28 etc/system-states
       0     1000  29 etc/table-loader
       0        0  2a etc/tpm/log
       0     2400  2b genroms/kvmvapic.bin
=> qfw read 1000 etc/acpi/rsdp
=> md.b 1000 14
00001000: 52 53 44 20 50 54 52 20 00 42 4f 43 48 53 20 00  RSD PTR .BOCHS .
00001010: 40 1c 00 00                                      @...

This shows dumping the E820 table, showing the emulated RAM as well as some reserved memory:

=> qfw e820
        Addr        Size  Type
  fd00000000   300000000  Reserved
           0    20000000  RAM
=>

Configuration

The qfw command is only available if CONFIG_CMD_QFW=y.