With the 'execute-in-place' patch to boot directly from CE0, we see a large
impact on boot time.
The overhead for the OpenBMC firmware images using the a custom U-Boot
is around 2 seconds, which is fine, but with a U-Boot from mainline,
it takes an extra 50 seconds or so to reach Linux. A quick survey on
the number of reads performed on the flash memory region gives the
following figures :
With the 'execute-in-place' patch to boot directly from CE0, we see a large impact on boot time.
The overhead for the OpenBMC firmware images using the a custom U-Boot is around 2 seconds, which is fine, but with a U-Boot from mainline, it takes an extra 50 seconds or so to reach Linux. A quick survey on the number of reads performed on the flash memory region gives the following figures :
OpenBMC U-Boot 922478 (~ 3.5 MBytes) Mainline U-Boot 20569977 (~ 80 MBytes)
QEMU must be trashing the TCG TBs and reloading text very often. Some addresses are read more than 250.000 times.