Re: Panic: attempted pmap_enter on 2MB page

2010-10-08 Thread Alan Cox
Kurt Alstrup wrote: Apologies for late response, wanted to check the code again. On 10/07/2010 10:03 AM, Alan Cox wrote: Alan Cox wrote: At a high-level, I agree with much of what you say. In particular, if pmap_enter() is applied to a virtual address that is already mapped by a large page

Re: Panic: attempted pmap_enter on 2MB page

2010-10-08 Thread Kurt Alstrup
Apologies for late response, wanted to check the code again. On 10/07/2010 10:03 AM, Alan Cox wrote: > Alan Cox wrote: > At a high-level, I agree with much of what you say. In particular, if > pmap_enter() is applied to a virtual address that is already mapped by a large > page, the reported pan

Re: Panic: attempted pmap_enter on 2MB page

2010-10-07 Thread Alan Cox
Kurt Alstrup wrote: Up front disclaimer: I may very well be wrong on this.. At a high-level, I agree with much of what you say. In particular, if pmap_enter() is applied to a virtual address that is already mapped by a large page, the reported panic could result. However, barring bugs,

Re: Panic: attempted pmap_enter on 2MB page

2010-10-06 Thread Alan Cox
Dave Hayes wrote: Alan Cox writes: When you build your kernel for this ISO are you increasing the value of NKPT? No. I was under the impression that this value auto-tunes on amd64, is that correct? After initialization, yes. However, the kernel starts out with just NKPT page ta

Re: Panic: attempted pmap_enter on 2MB page

2010-10-06 Thread Dave Hayes
Alan Cox writes: > When you build your kernel for this ISO are you increasing the value of > NKPT? No. I was under the impression that this value auto-tunes on amd64, is that correct? -- Dave Hayes - Consultant - Altadena CA, USA - d...@jetcafe.org >>> The opinions expressed above are entirely

Re: Panic: attempted pmap_enter on 2MB page

2010-10-06 Thread Alan Cox
Dave Hayes wrote: Alan Cox writes: [snip] Is this problem reproducible? I don't recall if you mentioned that earlier. Sort of. It seems that everytime I generate a bootable FreeBSD ISO, a die is rolled. If it comes up a certain number then it crashes, otherwise it's fine. ;) My

Panic: attempted pmap_enter on 2MB page

2010-10-06 Thread Kurt Alstrup
Up front disclaimer: I may very well be wrong on this.. This looks like a pmap bug I ran into a recently on a pre-release of 8.0. It's still present in stock 8.0, but I have not looked at 8.1 (see disclaimer). The bug was caused by a combination of a shortcut in pmap_unuse_pt() which didn't wipe

Re: Panic: attempted pmap_enter on 2MB page

2010-10-05 Thread Dave Hayes
Alan Cox writes: > There are two pieces of information that might be helpful: the value of > the global variable "kernel_vm_end" and the virtual address that was > passed to pmap_enter(). I'm afraid I don't have enough experience with this debugger to get these values with offhand commands. I c

Re: Panic: attempted pmap_enter on 2MB page

2010-10-04 Thread Alan Cox
Dave Hayes wrote: Alan Cox writes: I'm afraid that I can't offer much insight without a stack trace. At initialization time, we map the kernel with 2MB pages. I suspect that something within the kernel is later trying to change one those mappings. If I had to guess, it's related to the mfs

Re: Panic: attempted pmap_enter on 2MB page

2010-10-04 Thread Dave Hayes
Alan Cox writes: > I'm afraid that I can't offer much insight without a stack trace. At > initialization time, we map the kernel with 2MB pages. I suspect that > something within the kernel is later trying to change one those mappings. > If I had to guess, it's related to the mfs root. Here is

Re: Panic: attempted pmap_enter on 2MB page

2010-10-03 Thread Alan Cox
On Sat, Oct 2, 2010 at 9:11 PM, Dave Hayes wrote: > What does the above mentioned panic mean? I'm booting from > an mfsroot off of a DVD with a loader.conf like this: > > autoboot_delay="5" > mfsroot_load="YES" > mfsroot_type="mfs_root" > mfsroot_name="/mfsboot" > vfs.root.mountfrom="ufs:md0

Panic: attempted pmap_enter on 2MB page

2010-10-02 Thread Dave Hayes
What does the above mentioned panic mean? I'm booting from an mfsroot off of a DVD with a loader.conf like this: autoboot_delay="5" mfsroot_load="YES" mfsroot_type="mfs_root" mfsroot_name="/mfsboot" vfs.root.mountfrom="ufs:md0" vfs.root.mountfrom.options="rw" kern.ipc.nmbclusters=32768 net