Re: [Crash-utility] Question about ARM module address range
Hi Dave
I have taken a short look at modules_vaddr and module_end and I have both
seen relevant data:
crash> help -m
modules_vaddr: bf000000
modules_end: bfffffff
and data similar to what you see. What I also have seen is that when
modules are loaded then modules_vaddr and modules_end seems correct and
when no modules have been loaded then strange values are presented. I have
looked at too few examples to be certain that this is "always" true.
I assume (not checked in source code) that no vmalloc area is allocated
for modules if no modules are loaded. Then the function
first_vmalloc_address() will return data which is stored in modules_vaddr
but has nothing to do with this.
So I think that the question is what values should modules_vaddr and
modules_end have if no modules are loaded. Does it matter, except that it
might be confusing for a user? Looking at arm.c where modules_vaddr and
modules_end are used, I think the code will behaves correctly (by luck?!),
also in the case of no modules.
Jan
Jan Karlsson
Senior Software Engineer
MIB
I don't have access to my sample ARM vmcores (on vacation), but none
of them have any modules loaded. So in those 3 cases, the vmalloc range
starts at either d0807000 or c6024000, and so the hardwired modules_end
is confusing. But it appears from your description that modules are put
in a their own virtual address region from bf00000 to bffffff, whereas
other vmalloc() calls generate virtual addresses above c000000?
(as shown by kmem -v). In that case, you're right, the code would
work as is. Anyway, it did confuse me a bit -- perhaps arm_cmd_mach()
should show different "KERNEL VMALLOC BASE" and "KERNEL MODULES BASE"
addresses, i.e., similar to x86_64?
Dave
Dave