[{"id":1768241,"web_url":"http://patchwork.ozlabs.org/comment/1768241/","msgid":"<8cf54de7-a40d-dbed-b491-7cdf7f3b67ff@linaro.org>","list_archive_url":null,"date":"2017-09-13T23:25:26","subject":"Re: [Qemu-devel] [PATCH 04/19] nvic: Add cached vectpending_prio\n\tstate","submitter":{"id":72104,"url":"http://patchwork.ozlabs.org/api/people/72104/","name":"Richard Henderson","email":"richard.henderson@linaro.org"},"content":"On 09/12/2017 11:13 AM, Peter Maydell wrote:\n> Instead of looking up the pending priority\n> in nvic_pending_prio(), cache it in a new state struct\n> field. The calculation of the pending priority given\n> the interrupt number is more complicated in v8M with\n> the security extension, so the caching will be worthwhile.\n> \n> This changes nvic_pending_prio() from returning a full\n> (group + subpriority) priority value to returning a group\n> priority. This doesn't require changes to its callsites\n> because we use it only in comparisons of the form\n> execution_prio > nvic_pending_prio()\n> and execution priority is always a group priority, so\n> a test (exec prio > full prio) is true if and only if\n> (execprio > group_prio).\n> \n> (Architecturally the expected comparison is with the\n> group priority for this sort of \"would we preempt\" test;\n> we were only doing a test with a full priority as an\n> optimisation to avoid the mask, which is possible\n> precisely because the two comparisons always give the\n> same answer.)\n> \n> Signed-off-by: Peter Maydell \n> ---\n> include/hw/intc/armv7m_nvic.h | 2 ++\n> hw/intc/armv7m_nvic.c | 23 +++++++++++++----------\n> hw/intc/trace-events | 2 +-\n> 3 files changed, 16 insertions(+), 11 deletions(-)\n\nReviewed-by: Richard Henderson \n\n\nr~","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; 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