Re: [Crash-utility] [crash patch] Compute init_thread_union size
----- Original Message -----
On Thu, 2018-04-05 at 09:27 -0400, Dave Anderson wrote:
>
> ----- Original Message -----
> > Greetings,
> >
> > I know absolutely nothing about how crash maintenance is done, and very
> > damn little about crash's gizzard, so please consider the below a bug
> > report, a patch.. or bloody annoying spam, as you see fit.
>
> Hi Mike,
>
> No, it's most definitely appreciated. Normally patches are posted on the
> crash utility mailing list (crash-utility(a)redhat.com), but this is fine.
>
> And speaking of the mailing list, there was a bug report and subsequent
> thread yesterday concerning this issue:
>
> https://www.redhat.com/archives/crash-utility/2018-April/msg00000.html
>
> It was unresolved because the thread_union still exists in the most
> recent upstream sources, and I can still see the union declaration
> in the most recent Fedora kernel.
It still exists, but...
homer:..kernel/linux-4.15 # objdump -t vmlinux|grep thread_union
ffffffff81e00000 g O .data 0000000000004000 init_thread_union
^^^^
homer:..kernel/linux-master # objdump -t vmlinux|grep thread_union
ffffffff81e00000 g .data 0000000000000000 init_thread_union
^^^^
...it's size went missing at the referenced commit.
Right, but the crash utility never dealt with the "init_thread_union"
data symbol, but rather uses the declaration of the "thread_union"
union, which still exists in today's linux-git:
union thread_union {
#ifndef CONFIG_ARCH_TASK_STRUCT_ON_STACK
struct task_struct task;
#endif
#ifndef CONFIG_THREAD_INFO_IN_TASK
struct thread_info thread_info;
#endif
unsigned long stack[THREAD_SIZE/sizeof(long)];
};
So I'm guessing that the x86_64 arch never references the thread_union
from include/linux/sched.h, and therefore has no need to put it in the
vmlinux debuginfo data?
Dave
-Mike