diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/xz/xz.1 | 38 |
1 files changed, 31 insertions, 7 deletions
diff --git a/src/xz/xz.1 b/src/xz/xz.1 index b489fd35..3c09309b 100644 --- a/src/xz/xz.1 +++ b/src/xz/xz.1 @@ -6,7 +6,7 @@ .\" This file has been put into the public domain. .\" You can do whatever you want with this file. .\" -.TH XZ 1 "2024-01-22" "Tukaani" "XZ Utils" +.TH XZ 1 "2024-01-23" "Tukaani" "XZ Utils" . .SH NAME xz, unxz, xzcat, lzma, unlzma, lzcat \- Compress or decompress .xz and .lzma files @@ -1866,14 +1866,38 @@ Since the BCJ-filtered data is usually compressed with LZMA2, the compression ratio may be improved slightly if the LZMA2 options are set to match the alignment of the selected BCJ filter. -For example, with the IA-64 filter, it's good to set -.B pb=4 -or even +Examples: +.RS +.IP \(bu 3 +IA-64 filter has 16-byte alignment so .B pb=4,lp=4,lc=0 +is good with LZMA2 (2^4=16). -The x86 filter is an exception; -it's usually good to stick to LZMA2's default -four-byte alignment when compressing x86 executables. +.IP \(bu 3 +RISC-V code has 2-byte or 4-byte alignment +depending on whether the file contains +16-bit compressed instructions (the C extension). +When 16-bit instructions are used, +.B pb=2,lp=1,lc=3 +or +.B pb=1,lp=1,lc=3 +is good. +When 16-bit instructions aren't present, +.B pb=2,lp=2,lc=2 +is the best. +.B readelf \-h +can be used to check if "RVC" +appears on the "Flags" line. +.IP \(bu 3 +ARM64 is always 4-byte aligned so +.B pb=2,lp=2,lc=2 +is the best. +.IP \(bu 3 +The x86 filter is an exception. +It's usually good to stick to LZMA2's defaults +.RB ( pb=2,lp=0,lc=3 ) +when compressing x86 executables. +.RE .IP "" All BCJ filters support the same .IR options : |