Hi everyone,
I'm looking into how to speed up the build process and noticed that our build
uses LZMA to encrypt the main firmware volume. Since it's quite big it takes a
while but only uses one CPU thread.
LZMA2 is a version of LZMA which can be multi-threaded and achieve much faster
compression times. I did a quick benchmark using the `xz` command-line tool,
which uses a modified version of the LZMA SDK that EDK2 uses. The results are:
Uncompressed size: 64M
| Algo | Comp Time | Decomp Time | Size | Threads |
| ----- | --------- | ----------- | ---- | ------- |
| LZMA | 19.67s | 0.9s | 9.1M | 1 |
| LZMA2 | 20.11s | 1.2s | 9.2M | 1 |
| LZMA2 | 8.31s | 1.0s | 9.4M | 4 |
Using those commands:
time xz --format=lzma testfile
time unlzma testfile.lzma
time xz --lzma2 testfile
time unxz testfile.xz
time xz -T4 --lzma2 testfile
time unxz testfile.xz
This is quite a significant improvement of build time, while decompression time
and size only slightly increase. If that's a concern, then LZMA2 could be used
for development only.
I haven't investigated the details of how to support this in the code but it
appears to be a simple change, since the LZMA SDK that we use already supports
LZMA2.
What do you think?