On 12/07/2015 02:25 AM, Stewart Smith wrote: > Cédric Le Goater <c...@fr.ibm.com> writes: >> On 11/28/2015 08:59 AM, Benjamin Herrenschmidt wrote: >>> On Fri, 2015-11-27 at 11:21 +0100, Alexander Graf wrote: >>>> >>>> How does real hardware store petitboot? If it's flash, you could pass it >>>> in using -pflash and thus model things even more closely and allow users >>>> to just take the ROM image as is. >>> >>> It is a flash image, we could use an Open Power machine flash image "as-is" >>> provided we taught qemu to extract skiboot (aka OPAL) from it. >> >> Couldn't we add an offset argument to load_image_targphys() or make that >> an extra routine ? If so, we could then load directly from an openpower >> pnor file. >> >> I gave it a quick (and dirty) try and a powernv guest runs fine up to >> petitboot with just : >> >> qemu-system-ppc64 -m 2G -M powernv -bios >> ~/work/open-power/images/palmetto.pnor -nographic -nodefaults -serial stdio >> >> The pnor file is compiled from github. The patch is below (without the dirty >> cut and paste I did in loader.c). The offset for the PAYLOAD and BOOTKERNEL >> partitions are hard coded but I guess we don't need to read the flash >> partition >> table in qemu, not yet. > > One downside to this is that if we don't fall back to being able to load > skiboot.lid it becomes more annoying to boot a gcov enabled skiboot as > typical PNOR layout only gives 1MB for skiboot, and gcov builds bloat > that a *lot*.
I guess that what we can imagine having a bigger partition for skiboot in the case of gcov ? This will require a custom pnor build. Might be too complex. Or we could use a -pflash option to load the pnor and an optional -bios for skiboot if we want a custom one. > We probably don't want NVRAM writes going back to a single system wide > PNOR image too, so while using pnor file is great for simulating what > hardware does, may not work as the solution for long term model. we can use a memory backend to start with, which is also much simpler than having to handle the block backend like the cfi pflash is doing. a guest could use its own private pnor if a block backend is needed. C.
