Re: [PATCH 1/2] kvm-unit-tests: Add a func to run instruction in emulator

[Gleb Natapov <gleb@redhat.com>]

On Thu, Jun 20, 2013 at 01:48:39AM +0800, Gmail wrote:
> 
> 在 2013-6-20，0:03，Gleb Natapov <gleb@redhat.com> 写道：
> 
> > On Wed, Jun 19, 2013 at 11:07:18PM +0800, 李春奇 <Arthur Chunqi Li> wrote:
> >> Hi Gleb,
> >> This version can set %rsp before trapping into emulator, because
> >> insn_page and alt_insn_page is statically defined and their relative
> >> position to (save) is fixed during execution.
> > The position of the code is not fixed during execution since you execute
> > it from a virtual address obtained dynamically by vmap() and the address
> > is definitely different from the one the code was compiled for, but if
> > you look at the code that compile actually produce you will see that it
> > uses absolute address to access "save" and this is why it works. I
> > wounder why compiler decided to use absolute address this time, Paolo?
> > 
> >> In this way, test case of test_mmx_movq_mf needs to pre-define its own
> >> stack, this change is in the next patch.
> >> 
> >> In this version, insn_ram is initially mapped to insn_page and them
> >> each call to insn_page/alt_insn_page are all via insn_ram. This trick
> >> runs well but I don't know why my previous version causes error.
> > Because previous version tried to use install_page() on a large page
> > mapped region and the function does not know how to handle that.
> I don't quite understand what you mean here. What is the differences between large page and 4k page in this test case?
Test assumes 4k page size.

> Maybe I don't understand the differences of install_pte() with 4k page and 2m pages.
May be. You cannot install 4k page in place of 2m page before breaking
the later to 512 4k pages.

--
			Gleb.