Talk:Interrupt flag
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CLI a memory barrier?
editI looked through the Intel manuals searching for this information, and I cannot find a truly definitive answer. In chapter 7, volume 3 of the manual, it has information on memory ordering and serializing instructions, in which CLI is not listed as a memory barrier or a serializing instruction. I am not claiming that CLI is not a membar; in fact, intuition would tell me that it is. However, I'd like to get a definitive answer before we put this sort of information up on the page. http://www.intel.com/design/pentium4/manuals/index_new.htm
- Be sure to also look up the effects of changing the EFLAGS register. I may be simply miss-remembering what the effect really was. Jsmethers 06:21, 23 December 2005 (UTC)
- It may have been that chaging the IF flag in the EFLAGS register caused the processor to synchronize the instruction stream, and thus more or less made CLI and STI slow operations. Jsmethers 06:24, 23 December 2005 (UTC)
Neither CLI or STI are memory barriers since they are not listed in that table in the manual. There is no reason for them to be, although of course implementations may chose to make them serializing. I'm removing the incorrect statement from this page. David.kaplan 04:38, 3 May 2007 (UTC)
popf
editThe section on popf was slightly incorrect - popf only presents problems when trying to emulate protected mode programs (where IF is ignored if CPL>IOPL), since popf causes a #GP when IOPL<3 and in virtual-8086 mode. —Preceding unsigned comment added by AntiStatic (talk • contribs) 06:57, 12 July 2009 (UTC)
old DOS programs removal
editThe section regarding the mis-use of the Interrupt flag seems extraneous and not helpful in explaining the correct use. I propose removing it. DGerman (talk) 16:16, 14 August 2021 (UTC)
Setting and clearing
editThe first sentence of Setting and clearing section seems incomplete to me. Though I think the author/s intend for it to connect with the section title, reading it still feels incomplete. I propose changing it into "In a system using x86 architecture, the instructions CLI (Clear Interrupt) and STI (Set Interrupt) instructions are used." Marshblocker28 (talk) 09:50, 5 January 2022 (UTC)