| A simple x86 firmware that can boot Linux. |
| |
| Most of QEMU's 500-700 ms startup time is spent: |
| |
| * in the dynamic linker. This can be reduced by 150 ms simply by |
| compiling a stripped down QEMU: |
| |
| ./configure --disable-libssh2 --disable-tcmalloc --disable-glusterfs \ |
| --disable-seccomp --disable-{bzip2,snappy,lzo} --disable-usb-redir \ |
| --disable-libusb --disable-smartcard-nss --disable-libnfs \ |
| --disable-libiscsi --disable-rbd --disable-spice --disable-attr \ |
| --disable-cap-ng --disable-linux-aio --disable-uuid --disable-brlapi \ |
| --disable-vnc-{jpeg,tls,sasl,png,ws} --disable-rdma --disable-bluez \ |
| --disable-fdt --disable-curl --disable-curses --disable-sdl \ |
| --disable-gtk --disable-tpm --disable-vte --disable-vnc \ |
| --disable-xen --disable-opengl --target-list=x86_64-softmmu |
| |
| * in the BIOS. qboot saves another 150 ms. |
| |
| * in fw_cfg. This is fixed by putting kernel and initrd in a CoreBoot cbfs |
| image, and doing a memory copy from NVDIMM or flash instead of using fw_cfg. |
| Right now only flash is supported. 350 ms are saved, bringing the startup |
| time down to 60 ms. |
| |
| Usage |
| ===== |
| |
| fw_cfg based example: |
| |
| $ qemu-kvm -bios bios.bin \ |
| -kernel /boot/vmlinuz-4.0.3-300.fc22.x86_64 \ |
| -serial mon:stdio -append 'console=ttyS0,115200,8n1' |
| |
| cbfs-based example (pflash isn't the definitive interface though): |
| |
| $ dd if=/dev/zero of=boot.bin bs=4096 count=1 |
| $ cbfstool cbfs.rom create -s 8128k -B boot.bin -m x86 -o 0x1000 |
| $ cbfstool cbfs.rom add -f /boot/vmlinuz-4.0.3-300.fc22.x86_64 -n vmlinuz -t raw |
| $ echo 'console=ttyS0,115200,8n1' > cmdline |
| $ cbfstool cbfs.rom add -f cmdline -n cmdline -t raw |
| $ qemu-kvm -drive if=pflash,file=bios.bin,readonly=on \ |
| -drive if=pflash,file=cbfs.rom,readonly=on \ |
| -serial mon:stdio |
| |
| TODO |
| ==== |
| |
| * SMBIOS tables |
| * Multiboot loading from pflash |
