On Wed, 2013-08-21 at 11:11 +0100, Ben Hutchings wrote: > On Wed, 2013-08-21 at 10:53 +0100, Ian Campbell wrote: > > On Wed, 2013-08-21 at 11:30 +0200, Bastian Blank wrote: > > > On Wed, Aug 21, 2013 at 09:00:14AM +0100, Ian Campbell wrote: > > > > On Tue, 2013-08-20 at 22:51 +0800, jida...@jidanni.org wrote: > > > > > product: Intel(R) Celeron(R) M processor 1.40GHz > > > > > capabilities: fpu fpu_exception wp vme de pse tsc msr mce > > > > > cx8 sep mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss tm > > > > > pbe up bts > > > > The kernel will always either boot or not boot (with a message from the > > > > very early loader about lack of PAE). On the system above it looks like > > > > it wouldn't boot due to lack of PAE. > > > > > > It is quite possible that this CPU actually supports PAE. They don't > > > show it until you try to enable it. > > > > Ah, I wasn't sure if the kernel would check for the CPUID bit and just > > fail or do something more clever to see if it worked. > > > > In any case my main point is that it will either work or not. There is > > no half working/data corrupting case. > > There might be if the CPUs that don't advertise PAE also weren't tested > for PAE functionality at manufacturing time.
Hrm, that's true I guess. I'm a bit surprised that the upstream guys just enable PAE blindy on systems which don't advertise it TBH, that's not very conservative, I could better imagine them whitelisting some machines which were known good. Looking at the kernel though, if CONFIG_X86_PAE is set then NEED_PAE is set, this is then included in REQUIRED_MASK0. If I'm reading it right then arch/x86/boot/cpucheck.c seems to want to require these bits to be set and it will eventually crap out in validate_cpu. I don't actually have a non-pae system to try this on though... > But if we make the 686-pae kernel refuse to boot without PAE advertised, > we'll also break currently working systems. Ian. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org