On 3/25/19 10:40 AM, Paul Durrant wrote: >> -----Original Message----- >> From: Xen-devel [mailto:xen-devel-boun...@lists.xenproject.org] On Behalf Of >> Jennifer Herbert >> Sent: 25 March 2019 14:24 >> To: Boris Ostrovsky <boris.ostrov...@oracle.com>; x...@kernel.org; >> xen-devel@lists.xenproject.org; >> linux-ker...@vger.kernel.org >> Cc: Juergen Gross <jgr...@suse.com>; Stefano Stabellini >> <sstabell...@kernel.org>; Ingo Molnar >> <mi...@redhat.com>; Borislav Petkov <b...@alien8.de>; H. Peter Anvin >> <h...@zytor.com>; Thomas Gleixner >> <t...@linutronix.de> >> Subject: Re: [Xen-devel] [PATCH] xen/pv: Add PV specific legacy_pic struct >> to expose legacy IRQs. >> >> >> >> On 21/03/19 17:49, Jennifer Herbert wrote: >>> >>> On 19/03/19 23:06, Boris Ostrovsky wrote: >>>> On 3/19/19 4:02 PM, Jennifer Herbert wrote: >>>>> The ACPI tables doesn't always contain all IRQs for legacy devices >>>>> such as RTC. Since no PIC controller is visible for a PV linux guest, >>>>> under Xen, legacy_pic currently defaults to the null_legacy_pic - with >>>>> reports no legacy IRQs. Since the commit "rtc: cmos: Do not assume >>>>> irq 8 for rtc when there are no legacy irqs" by Hans de Goede >>>>> (commit id: a1e23a42f1bdc00e32fc4869caef12e4e6272f26), the rtc now >>>>> incorrectly decides it has no irq it can use, for some hardware. >>>>> >>>>> This patch rectifies the problem by providing a xen legacy_pic >>>>> struct, which is much like the null_legacy_pic except that it >>>>> reports NR_IRQS_LEGACY irqs. >>>> I assume this is for dom0? >>>> >>>> Could there be the same problem with PVH dom0? (and if yes then this >>>> should probably go into arch/x86/xen/enlighten.c). >>>> >>>> -boris >>>> >>> I am doing this to fix a problem with dom0. DomU doesn't seem to have >>> an RTC, and so it is unaffected. >>> >>> I'm not familiar with PVH, but have now done some experiments. The RTC >>> on PVH seems broken - but not quite in the same way as PV. More >>> research is needed, however simply doing the same trick I did with PV >>> will not fix the issue. >>> >>> I'll look further into it. >>> >> The same problem does exist with PVH - however its worse with the >> presence of the IO-APIC, as with my patch it tries to set up with IRQ, >> and fails. I'm not sure how would be best to deal with this. >> However, the RTC seems broken even for machines without the ACPI omission. >> I can see fixing it for just PV doesn't seem too nice, but unsure how to >> fix this for PVH. I'm open to suggestions, but otherwise I'll put this >> on hold. > AFAICT from the code in libxl__arch_domain_prepare_config(), PVH domains > don't get an RTC, just a local APIC. >
That's true for domU but not for PVH dom0 I believe. Roger? -boris _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
