Hi Prakhar, On Thu, Jul 17, 2014 at 11:15 AM, Prakhar Deep <prakhard...@gmail.com> wrote: > Hi, > > > I am facing kernel panic when 2nd processor is executing it's reset > code while running a 32-bit OS as a VM (with PAE enabled) on ‘bhyve’ with > following parameters: > > 1. Number of vCPUs 2 or more, and > > 2. Memory 4GB or more > > When number of vCPU =1 and memory > 4GB i.e. PAE mode with only one CPU or > vCPU = 2 or more and memory < 4GB i.e non-PAE mode then VM comes up > successfully. The OS is able to bring up the boot processor but it panics > when AP is executing it's reset code. > > > The OS uses fixed kernel virtual addresses which are mapped by a level 2 > page table which is replicated for each CPU to allow some of these mappings > to be different on a > per-CPU basis. These pages act as storage for many global variables which > are used when processor is executing reset code. When a second (non-boot) > CPU comes up, we are seeing that per-CPU pages for this CPU are reset to > all zeroes when the second CPU sets the PGE flag in CR4. This then leads to > incorrect code paths. > > I am not able to understand why the pages mapped to AP are getting set to 0 > when PGE flag is set in CR4 as this does not happen for boot processor. If > i do not set PGE flag then pages are not set to 0 but the code panics some > where else but not due to zeroed out global values. > > I have tried FreeBSD i386 with PAE support compiled into the kernel on > Bhyve with >4GB RAM and 2 vCPUS and VM came up successfully. Also, the PGE > bit is set in the CR4 register for FreeBSD. > > > It will be helpful if anyone could throw some light on following points: > > > > 1. Why are the pages mapped to AP are being zeroed when PGE flag is set for > AP in it's CR4 ? >
It is hard to say but my guess would be that the 4 PDPTE registers in the VMCS are not being properly updated during AP spinup. It would be helpful to see the assembly instructions in the AP spinup code that modify %cr0, %cr4 and %cr3 to know for sure. > 2. Are there are any changes required in a 32-bit OS to boot it in PAE mode > with 4GB or more RAM and 2 or more vCPUS on Bhyve ? > No. > 3. Was FreeBSD (i386) kernel updated to boot on Bhyve with 4GB or more RAM > and 2 or more vCPUS ? > No. best Neel > Thanks. > > Prakhar > _______________________________________________ > freebsd-virtualization@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > To unsubscribe, send any mail to > "freebsd-virtualization-unsubscr...@freebsd.org" _______________________________________________ freebsd-virtualization@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"
