Date: Mon, 7 Nov 2016 13:46:27 -0800 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: freebsd-ppc@freebsd.org Subject: Re: Why Huge pages must be enabled to boot a FreeBSD VM? Message-ID: <be945590-dc6a-ed4d-ccec-9339fe9d04f0@freebsd.org> In-Reply-To: <0c4b5c7e-1078-4d42-426c-3091da17e501@br.ibm.com> References: <0c4b5c7e-1078-4d42-426c-3091da17e501@br.ibm.com>
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On 11/07/16 11:40, Breno Leitao wrote: > Hello, > > I am wondering why Huge pages must be enabled in the hypervisor (KVM) in > order to boot FreeBSD as a guest. > > I was facing the issue below, and then I found that I didn't have enough huge > pages available. Enabling the amount of huge pages available solved this issue. > > Kernel entry at 0x1023c0 ... > panic: Page replacement error: -4 > cpuid = 0 > KDB: stack backtrace: > #0 0x6144fc at ??+0 > #1 0x614598 at ??+0 > #2 0xa7b078 at ??+0 > #3 0xa31544 at ??+0 > #4 0xa33010 at ??+0 > #5 0xa7b480 at ??+0 > #6 0xa6b2bc at ??+0 > #7 0xa64c74 at ??+0 > #8 0x102458 at ??+0 > Uptime: 1s > > > If huge pages is not enabled, is there a way to proceed with normal pages > other than crashing the VM? > > Thank you, > Breno > > _______________________________________________ > freebsd-ppc@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-ppc > To unsubscribe, send any mail to "freebsd-ppc-unsubscribe@freebsd.org" > It is supposed to warn you about that in early boot, but I guess the warning is coming too late now. We should fix that. The FreeBSD kernel on powerpc64 critically relies on huge pages to create a direct-mapped region for physical memory. It is hard, though not impossible, to change this, as it requires a comprehensive rearchitecture of much of the memory management code. -Nathan
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