From: lkcl Date: Sat, 26 Oct 2019 00:52:24 +0000 (+0100) Subject: (no commit message) X-Git-Tag: convert-csv-opcode-to-binary~3840 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7e69d2172654814dfd91c13e607cbb4e8a140db7;p=libreriscv.git --- diff --git a/openpower.mdwn b/openpower.mdwn index ac5aaaf73..dc1db37a6 100644 --- a/openpower.mdwn +++ b/openpower.mdwn @@ -49,3 +49,18 @@ Store activation length in a CSR. 3 bits for subpage number. 4 bits for length, gives 7 bits. 4x7 is 28, then 3 bits can be used to specify "stack depth". Requirements are to have one instruction in each subpage which resets all the way back to PowerISA default. The other is a "back up stack by 1". + +## Branches + +Branches are fine as it is up to the compiler to decide whether to let the countdown run out. + +This is all a software / compiler / ABI issue. + +## Function calls. + +Storing and restoring the state of the page/subpage CSR should be done by the caller. Or, again, let the countdowns run out. + +If certain alternative configs are expected, they are part of the function ABI which must be spec'd. + +All of this is a software issue (compiler / ABI). +