Document the usage of 'fw' command
Signed-off-by: Miao Yan yanmiaobest@gmail.com --- Changes in v2: - various cleanup
doc/README.x86 | 36 +++++++++++++++++++++++++++++++++--- 1 file changed, 33 insertions(+), 3 deletions(-)
diff --git a/doc/README.x86 b/doc/README.x86 index 1271e5e..0687dc1 100644 --- a/doc/README.x86 +++ b/doc/README.x86 @@ -295,9 +295,39 @@ show QEMU's VGA console window. Note this will disable QEMU's serial output. If you want to check both consoles, use '-serial stdio'.
Multicore is also supported by QEMU via '-smp n' where n is the number of cores -to instantiate. Currently the default U-Boot built for QEMU supports 2 cores. -In order to support more cores, you need add additional cpu nodes in the device -tree and change CONFIG_MAX_CPUS accordingly. +to instantiate. U-Boot uses fw_cfg interface provided by QEMU to detect certain +system information, such as cpu number, so 'n' can be any number allowed by +QEMU. + +The fw_cfg interface in QEMU also provides information about kernel data, initrd +,command-line arguments and more. U-Boot supports directly accessing these informtion +from fw_cfg interface, this saves the time of loading them from hard disk or +network again, through emulated devices. To use it , simply providing them in +QEMU command line: + +$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -m 1024 -kernel /path/to/bzImage + -append 'root=/dev/sda1 console=ttyS0' -initrd /path/to/initrd -smp 8 + +Note: -initrd and -smp are both optional + +Then start QEMU, in U-Boot command line use the following U-Boot command to setup kernel: + + => fw +fw - QEMU firmware interface + +Usage: +fw <command> + - list : print firmware(s) currently loaded + - cpus : print online cpu number + - load <addr> : load kernel (if any) to address <addr> + +=> fw load +loading kernel to address 01000000, initrd 015dd010 + +Here the kernel (bzImage) is loaded to 01000000 and initrd is to 0x15dd010. Then, 'zboot' +can be used to boot the kernel: + +=> zboot 01000000 - 015dd010
CPU Microcode -------------