--compact bootloader restrictions lifted in 1903 and beyond
Posted: Mon May 13, 2019 8:57 pm
Wimlib currently maintains a hardcoded list of files that must never be compressed beyond XPRESS4K when doing a compact deployment.
As of Windows 10 version 1903, this is obsolete.
1903 can boot fine with both winload.efi and ntoskrnl.exe manually compressed as LZX, according to my own testing. (This required a bit of trickery, as Windows' compact.exe refuses to compress any file containing "winload" in its name - I ended up copying winload.efi to bootload.efi, compressing that, and editing BCD to point to bootload.efi instead of winload.efi. No such restriction exists for ntoskrnl.exe.)
Also in 1903, dism's /Compact seems to use XPRESS8K for all files, including ntoskrnl and winload.
I'm not sure which build introduced this change, but at least in 18362 and up, the blacklist can be safely ignored, and everything compressed with the user's selected compression mode.
As of Windows 10 version 1903, this is obsolete.
1903 can boot fine with both winload.efi and ntoskrnl.exe manually compressed as LZX, according to my own testing. (This required a bit of trickery, as Windows' compact.exe refuses to compress any file containing "winload" in its name - I ended up copying winload.efi to bootload.efi, compressing that, and editing BCD to point to bootload.efi instead of winload.efi. No such restriction exists for ntoskrnl.exe.)
Also in 1903, dism's /Compact seems to use XPRESS8K for all files, including ntoskrnl and winload.
I'm not sure which build introduced this change, but at least in 18362 and up, the blacklist can be safely ignored, and everything compressed with the user's selected compression mode.