Hi Andrei,
I've been talking to a few people about X86EmulatorPkg and their
experience with it hasn't been positive: apparently there are lots of
cases where it's failed to work (i.e. caused crashes) which is why it's
not been more widely used.
Since suggesting they try MultiArchUefiPkg they've said it's working
much better, and in fact some people have proceeded with enabling it in
their firmware.
I'm a bit confused about the licensing of MultiArchUefiPkg given the
license file says it's LGPL while it uses the GPL-licensed Unicorn library.
Does that mean the overall licensing for it will be GPL?
--
Rebecca
On 9/5/2024 11:32 PM, Andrei Warkentin via groups.io wrote:
Hey folks,
Sorry for the late response.
- My suggestion is not to replace, but augment. MultiArchUefiPkg is fairly new,
not particularly well adopted, surely with some flaws lurking here and there
and for certain with no guarantee of fitness or proof that it will work 100% or
100% better than X86EmulatorPkg for every single use case of X86EmulatorPkg in
the wild. X86EmulatorPkg has been around for a lot longer than its rewrite, and
I think the people actively using X86EmulatorPkg should continue to have the
option to continue using it.
- Unicorn has been a blessing and a curse, although abstracting the emulator
with an API seems like a winner. An API-compatible emulator or JIT is something
I've been thinking about, but not really doing anything about it for the
moment. So yes, actual licensing of binaries is cursed.
- All memory but the zero page is visible to the emulator. See
CpuNullReadCb/CpuNullWriteCb. See also TestNullDeref in
Application/EmulatorTest. I don't remember if I added the behavior because this
is what the original did, or because I actively tripped on the NULL accesses
from some x86 code I was testing...
A
-----Original Message-----
From: Ard Biesheuvel <a...@kernel.org>
Sent: Sunday, September 1, 2024 3:05 AM
To: Rebecca Cran <rebe...@bsdio.com>; Warkentin, Andrei
<andrei.warken...@intel.com>
Cc: devel@edk2.groups.io; quic_llind...@quicinc.com; Kinney, Michael D
<michael.d.kin...@intel.com>
Subject: Re: [PATCH] Emulator/X86EmulatorDxe: Replace with
MultiArchUefiPkg build
Hi Rebecca,
On Sun, 1 Sept 2024 at 00:33, Rebecca Cran <rebe...@bsdio.com> wrote:
Replace the old X86EmulatorDxe with one built from
https://github.com/intel/MultiArchUefiPkg. This is a much more modern,
recent implementation that's more reliable and is actively maintained.
Add driver binaries for both AArch64 and RISCV64, along with the
LoadOpRom application.
Signed-off-by: Rebecca Cran <rebe...@bsdio.com>
---
Emulator/X86EmulatorDxe/AArch64/EmulatorDxe.depex | Bin 0 -> 54
bytes
Emulator/X86EmulatorDxe/AArch64/EmulatorDxe.efi | Bin 0 -> 573440
bytes
Emulator/X86EmulatorDxe/AArch64/LoadOpRom.efi | Bin 0 -> 28672
bytes
Emulator/X86EmulatorDxe/README.md | 11 +++++++----
Emulator/X86EmulatorDxe/RISCV64/EmulatorDxe.depex | Bin 0 -> 54
bytes
Emulator/X86EmulatorDxe/RISCV64/EmulatorDxe.efi | Bin 0 -> 561216
bytes
Emulator/X86EmulatorDxe/RISCV64/LoadOpRom.efi | Bin 0 -> 30848
bytes
Emulator/X86EmulatorDxe/X86EmulatorDxe.depex | Bin 36 -> 0 bytes
Emulator/X86EmulatorDxe/X86EmulatorDxe.efi | Bin 913408 -> 0
bytes
Emulator/X86EmulatorDxe/X86EmulatorDxe.inf | 10 +++++++---
10 files changed, 14 insertions(+), 7 deletions(-)
Happy to see that this work has been absorbed into a project that will
improve and maintain it going forward.
However, according to the github.com repo Readme of
MultiArchUefiCpuPkg, these binaries include statically linked UniCorn builds,
which are a mix of LPGL and GPLv2, so you will need to update the LICENSE
file accordingly.
Also, glancing over the code, it seems like it removes the NULL pointer
dereference handling that the original X86EmulatorPkg has - this code was
added for a purpose, as some Nvidia option ROMs will happily dereference
NULL pointers, which happens to work on most older
X64 firmware because page 0x0 happens to be mapped. Perhaps Andrei can
comment on this point?
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