afterwards issue a matching number of read request to verify the content.

While doing it fix an off by 1 of i

* 'master' of github.com:cloudius-systems/osv: (26 commits)
  acpi: integrate acpica
  mmu: export phys_cast
  mmu: implement phys_to_virt()
  Add acpica license
  external: add acpi component architecture (acpica) package
  fix the glibc-testsuite reference
  move filesystem related headers to include/
  Move Java support to java/
  Disband 'kern/'
  Move core source files to core/
  Move some headers to 'include/'
  Rename 'includes/' to 'include/'
  add sleep() from musl
  add statvfs/fstatvfs support
  add statfs/fstatfs support
  create /tmp during startup
  add the glibc block test
  run: use all available host cpu features for maximum performance
  mmap: trap attempts to remap physical memory
  pthread: allocate a vma for thread stack
  ...

requests and wait for the answers.

Now basic data exchange seems to work (w/o interrupts yet)

Simpler than phys_cast sometimes.

I've also added an osv/ prefix to make sure we don't clash with system headers.

We probably should either adopt this globally or drop it, but I fear we'll run into
problems with the latter approach.

Various glibc tests need it.

The payload is likely to play games with the stack area (like mmap()ing guard
pages), so give it virtual memory to play with instead of physical memory.

Fixes crash with mode=release.

Exceptions are challenging on x64 because the ABI reserves 128 bytes below
%rsp for local variables; this will be overwritten by an exception or
interrupt.  We can't use -mno-red-zone because the payload may not have been
compiled for it.  Instead, use the interrupt stack stack table mechanism
and a separate stack for exceptions.  May fix random corruptions when timers
are used.

Look up the build directory from the running object.

glibc headers define various standard functions as macros, which breaks
the build.  #undef them in the source files.

It is illegal to put a field after a variable-length array, what's its offset?
Breaks mode=release.

* 'master' of github.com:cloudius-systems/osv:
  Changes misleading pci_conf_read/write to virtio_conf_read/write
  Split virtio_driver to virtio_device and virtio_driver
  external: update glibc-testsuite for .gitignore
  build: document Java build rules
  build: make ant quieter on quiet builds
  main: go back to running the payload, not tests
  build: allow setting the command line during build
  tests: add Java microbenchmark suite
  java: add support for launching a jar file
  bootfs: add currency.data
  add a manifest where the libc files come from
  add a real __assert_fail from musl
  add a basic bio layer

Silences 'Subproject commit -dirty' messages

Not completely silent unfortunately.