Warning: mysqli::__construct(): (HY000/1203): User howardkn already has more than 'max_user_connections' active connections in D:\Inetpub\vhosts\howardknight.net\al.howardknight.net\includes\artfuncs.php on line 21
Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!weretis.net!feeder9.news.weretis.net!news.nk.ca!rocksolid2!i2pn2.org!.POSTED!not-for-mail From: mitchalsup@aol.com (MitchAlsup1) Newsgroups: comp.arch Subject: Re: Constant Stack Canaries Date: Wed, 16 Apr 2025 21:13:43 +0000 Organization: Rocksolid Light Message-ID: <694fc2e37e0bcb6de19c0e1d1d0f0042@www.novabbs.org> References: <760b3834d1202502f5f63e52b51cfdc8@www.novabbs.org> <1a0a4bdf578ae29ba9c2d20f19d0adde@www.novabbs.org> <07451feab34704115f6b9487cbcd6df9@www.novabbs.org> <1GtLP.2610861$TBhc.2239154@fx16.iad> <005f8b290a83aa0b6c1714369a1e540d@www.novabbs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Info: i2pn2.org; logging-data="646418"; mail-complaints-to="usenet@i2pn2.org"; posting-account="o5SwNDfMfYu6Mv4wwLiW6e/jbA93UAdzFodw5PEa6eU"; User-Agent: Rocksolid Light X-Rslight-Site: $2y$10$gT/aUkELieMm3cFSH59RUe9ohb9yYVcnvHv9NSKY46iQ85JCxwf3S X-Rslight-Posting-User: cb29269328a20fe5719ed6a1c397e21f651bda71 X-Spam-Checker-Version: SpamAssassin 4.0.0 Bytes: 3386 Lines: 45 On Wed, 16 Apr 2025 14:07:36 +0000, Scott Lurndal wrote: > mitchalsup@aol.com (MitchAlsup1) writes: ---------snip----------- >> >>So, if core is running HyperVisor at priority 15 and a user interrupt >>arrives at a higher priority but directed at GuestOS (instead of HV) >>does:: >>a) HV continue leaving higher priority interrupt waiting. >>b) switch back to GuestOS for higher priority interrupt--in such >>. a way that when GuestOS returns from interrupt HV takes over >>. from whence it left. > > ARM, for example, splits the per-core interrupt priority range into > halves > - one half is assigned to the secure monitor and the other is assigned > to the > non-secure software running on the core. Thus, my predilection for 64-priority levels (rather than ~8 as suggested by another participant) allows for this distribution of priorities across layers in the SW stack at the discretion of trustable-SW. > Early hypervisors would field > all > non-secure interrupts and either handle them itself or inject them into > the guest. The first ARM64 cores would field all interrupts in the HV > and the int controller had special registers the HV could use to inject > interrupts > into the guest. The overhead was not insignifcant, so they added > a mechanism to allow some interrupts to be directly fielded by the > guest itself - avoiding the round trip through the HV on every interrupt > (called virtual LPIs). Given 4 layers in the stack {Secure, Hyper, Super, User} and we have interrupts targeting {Secure, Hyper, Super}, do we pick up any liability or do we gain flexibility by being able to target interrupts directly to {user} ?? (the 4th element). Roughly: HW maintains 4 copies of state and generally indexes state with a 2-bit value, and the "structure" of thread-header is identical between layers; thus, indexing down to {user} falls out for free. {{But I could be off my rocker...again}}