Bug 969 - 64-bit variants of setvl, svshape, svstep and svindex
Summary: 64-bit variants of setvl, svshape, svstep and svindex
Status: CONFIRMED
Alias: None
Product: Libre-SOC's first SoC
Classification: Unclassified
Component: Specification (show other bugs)
Version: unspecified
Hardware: Other Linux
: --- enhancement
Assignee: Luke Kenneth Casson Leighton
URL:
Depends on:
Blocks: 952
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Reported: 2022-10-24 01:07 BST by Luke Kenneth Casson Leighton
Modified: 2022-10-25 02:53 BST (History)
2 users (show)

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NLnet milestone: NLnet.2022-08-051.OPF
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Description Luke Kenneth Casson Leighton 2022-10-24 01:07:53 BST 
the 32 bit variants turn out to be severely under pressure, cf chacha20
needing 3D svshape2.
Comment 1 Jacob Lifshay 2022-10-25 02:53:31 BST 
please have bits that are specifically reserved for enabling future regfile extensions, last time setvl had that but you ended up using it for something else, i was eventually ok with that because i figured we could cram those extension bits in the prefix of sv.setvl

if you can reserve 3 bits at minimum, preferably 5-8 bits, that should be good. we'd need 3 bits for a mode and the rest for immediate extension to support larger VL/MAXVL.