Date: Sat, 10 Sep 2016 15:41:38 -0500 From: Krzysztof Parzyszek <kristof@swissmail.org> To: Mark Millard <markmi@dsl-only.net> Cc: Jukka Ukkonen <jau789@gmail.com>, freebsd-ppc@freebsd.org Subject: Re: PowerMac G5 hangs/crashes on boot: 10.2, 11.0-RCx Message-ID: <b39a5ae1-7aa5-a71f-3aff-221fc9c2e4da@swissmail.org> In-Reply-To: <0A9EB3C7-F430-4F82-9B09-632754BB82C8@dsl-only.net> References: <6ad00a2d-4213-18b8-7974-534aa3758837@swissmail.org> <E90BB066-47C9-4626-BE6C-5D15ECA0E4EE@gmail.com> <db0aa91b-aa79-689a-e901-437e18b49b81@swissmail.org> <0A9EB3C7-F430-4F82-9B09-632754BB82C8@dsl-only.net>
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On 9/9/2016 3:21 PM, Mark Millard wrote: > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=205458 (from 2015-Dec-20) > > It reports as the technique: > >> The change is in ofw_sprg_prepare of sys/powerpc/ofw/ofw_machdep.c and could look something like (presented in a form to show new/PowerMacG5-Specific code and old general code): >> >> #ifdef POWERMAC_G5_SPECIFIC_BUILD >> __asm __volatile("mfsprg0 %0\n\t" >> "mtsprg1 %1\n\t" >> "mtsprg2 %2\n\t" >> "mtsprg3 %3\n\t" >> : "=&r"(ofw_sprg0_save) >> : "r"(ofmsr[2]), >> "r"(ofmsr[3]), >> "r"(ofmsr[4])); >> #else >> // The historical code: >> __asm __volatile("mfsprg0 %0\n\t" >> "mtsprg0 %1\n\t" >> "mtsprg1 %2\n\t" >> "mtsprg2 %3\n\t" >> "mtsprg3 %4\n\t" >> : "=&r"(ofw_sprg0_save) >> : "r"(ofmsr[1]), >> "r"(ofmsr[2]), >> "r"(ofmsr[3]), >> "r"(ofmsr[4])); >> #endif >> >> In other words: for PowerMac G5's omit the mtsprg0 from ofmsr[1]: leave the register as it already is instead of resetting it. The value in ofmsr[1] is inappropriate to the context. I deliberately kept the change minimal and left in all other code related to the register. > Hi Mark, I reinstalled 10.3, and it boots *sometimes*. I cannot try this change though, because it hangs well before the kernel finishes building. The custom kernel I had before was quite stable, once it booted, but at the moment I cannot get any kernel to build. -Krzysztof
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