This observation came up during the review of "Move tlbie[l] to decode tree" patch [1] and it seems useful enough to be added in the docs.
[1] https://lists.gnu.org/archive/html/qemu-devel/2022-07/msg02195.html Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com> --- docs/devel/decodetree.rst | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/docs/devel/decodetree.rst b/docs/devel/decodetree.rst index 49ea50c2a7..6bcb94f449 100644 --- a/docs/devel/decodetree.rst +++ b/docs/devel/decodetree.rst @@ -110,7 +110,9 @@ A *fixedbit_elt* describes a contiguous sequence of bits that must be 1, 0, or don't care. The difference between '.' and '-' is that '.' means that the bit will be covered with a field or a final 0 or 1 from the pattern, and '-' means that the bit is really -ignored by the cpu and will not be specified. +ignored by the cpu and will not be specified. The same format can +be reused in multiple patterns by using '.' and let the pattern +decide whether the given bit will be ignored or not. A *field_elt* describes a simple field only given a width; the position of the field is implied by its position with respect to other *fixedbit_elt* -- 2.36.1