Cc'ing Laurent and Alex. On 12/17/20 6:14 AM, Brian Cain wrote: > My team is working on sysemu support for Hexagon. We've made some good > progress so far and we'll work on upstreaming after Taylor’s hexagon > linux-user patch series lands. > > The only use case we have focused on with sysemu is booting/running elf > programs. Both "-device loader,file=..." or "-kernel" are effective and work > similarly. We have implemented "angel calls" (semihosting) to do host I/O. > We have not yet tried using the QEMU semihosting features/cmdline args, but > may explore that option. > > One feature we'd like to integrate is a guest library search path feature. > The existing hexagon simulator program distributed in the Hexagon SDK has a > command line option, “--usefs". The manual states that it “Cause[s] the > simulator to search for files in the directory with the specified path. It is > used for accessing shared object files that are loaded during program > execution.” If the guest OS has a loader that tries to resolve an executable > or library's DT_NEEDED shared object libraries, we would want QEMU angel > calls to be able to search a user specified host-path for the toolchain > language support libraries. > > This feature is like the functionality in QEMU’s “QEMU_LD_PREFIX” environment > variable used by linux-userspace. So, one idea was to just (ab)use this > interface to mean the same thing for sysemu. We could make it a > target-specific hexagon feature, if it doesn’t make sense to have it as > target-independent. And if it makes sense we could qualify it like > HEXAGON_QEMU_LD_PREFIX. > > If not this environment variable, is there an existing QEMU feature that maps > well here? Or is there a better interface that we should consider instead? > > -Brian >
