Breakpoints in crash
by Dheeraj Sangamkar
Hi,
I use crash regularly(everyday) and its fabulous.
I dont know if there is a way to specify break points in kernel code
using crash during live debugging.
There are kernel debuggers from some OSes where this is possible. I am
wondering if there is a plan to include breakpointing functionality in
crash sometime in the future.
Dheeraj
15 years
Re: [Crash-utility] memory requirement for crash tool
by Dave Anderson
----- "Dharmosoth Seetharam" <seetharam_21(a)yahoo.com> wrote:
> Hi,
>
> I have a question regarding the memory requirement for crash tool
> to start analyzing or extract few command's results from the
> kernel core of size more than 50G.
>
> my system details
> arch : x86_64
> memory: 128M
>
> But I want to analyze kernel core of size 50G+.
>
> Now I am unable to do that.
>
> Can you please tell me how much memory it needs to get atleast "bt"
> information?
No I can't -- I have no idea. 128MB is pretty pitiful. But with
enough swap I would guess that the crash session will come up eventually?
You might try adding "--active" to the command line, which will
only gather task data for the active task on each cpu.
Dave
15 years
[PATCH] Add i386 linux-2.6.30 support.
by Ken'ichi Ohmichi
Hi,
The latest crash (version 4.0-8.11) fails on i386 linux-2.6.30:
# crash -s vmlinux vmcore
crash: cannot resolve: "hardirq_ctx"
#
The reason is that both hardirq_ctx and softirq_ctx have been defined
by DEFINE_PER_CPU() since linux-2.6.30. This change is the following:
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
[snip]
-static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
-static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
+static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);
+static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);
By this patch, the crash utility can read the dumpfile of i386 linux-2.6.30.
Thanks
Ken'ichi Ohmichi
Signed-off-by: Ken'ichi Ohmichi <oomichi(a)mxs.nes.nec.co.jp>
---
--- a/task.c 2009-07-01 00:31:20.000000000 +0900
+++ b/task.c 2009-07-06 15:37:35.000000000 +0900
@@ -488,10 +488,27 @@ irqstacks_init(void)
thread_info_buf = GETBUF(SIZE(irq_ctx));
- i = get_array_length("hardirq_ctx", NULL, 0);
- get_symbol_data("hardirq_ctx",
- sizeof(long)*(i <= NR_CPUS ? i : NR_CPUS),
- &tt->hardirq_ctx[0]);
+ if (symbol_exists("hardirq_ctx")) {
+ i = get_array_length("hardirq_ctx", NULL, 0);
+ get_symbol_data("hardirq_ctx",
+ sizeof(long)*(i <= NR_CPUS ? i : NR_CPUS),
+ &tt->hardirq_ctx[0]);
+ } else if (symbol_exists("per_cpu__hardirq_ctx")) {
+ if ((kt->flags & SMP) && (kt->flags & PER_CPU_OFF)) {
+ for (i = 0; i < NR_CPUS; i++) {
+ if (!kt->__per_cpu_offset[i])
+ continue;
+ tt->hardirq_ctx[i] =
+ symbol_value("per_cpu__hardirq_ctx") +
+ kt->__per_cpu_offset[i];
+ }
+ } else {
+ tt->hardirq_ctx[0] =
+ symbol_value("per_cpu__hardirq_ctx");
+ }
+ } else {
+ error(FATAL, "cannot get hardirq_ctx.");
+ }
for (i = 0; i < NR_CPUS; i++) {
if (!(tt->hardirq_ctx[i]))
@@ -509,10 +526,27 @@ irqstacks_init(void)
ULONG(thread_info_buf+OFFSET(thread_info_task));
}
- i = get_array_length("softirq_ctx", NULL, 0);
- get_symbol_data("softirq_ctx",
- sizeof(long)*(i <= NR_CPUS ? i : NR_CPUS),
- &tt->softirq_ctx[0]);
+ if (symbol_exists("softirq_ctx")) {
+ i = get_array_length("softirq_ctx", NULL, 0);
+ get_symbol_data("softirq_ctx",
+ sizeof(long)*(i <= NR_CPUS ? i : NR_CPUS),
+ &tt->softirq_ctx[0]);
+ } else if (symbol_exists("per_cpu__softirq_ctx")) {
+ if ((kt->flags & SMP) && (kt->flags & PER_CPU_OFF)) {
+ for (i = 0; i < NR_CPUS; i++) {
+ if (!kt->__per_cpu_offset[i])
+ continue;
+ tt->softirq_ctx[i] =
+ symbol_value("per_cpu__softirq_ctx") +
+ kt->__per_cpu_offset[i];
+ }
+ } else {
+ tt->softirq_ctx[0] =
+ symbol_value("per_cpu__softirq_ctx");
+ }
+ } else {
+ error(FATAL, "cannot get softirq_ctx.");
+ }
for (i = 0; i < NR_CPUS; i++) {
if (!(tt->softirq_ctx[i]))
15 years
memory requirement for crash tool
by Dharmosoth Seetharam
Hi,
I have a question regarding the memory requirement for crash tool
to start analyzing or extract few command's results from the
kernel core of size more than 50G.
my system details
arch : x86_64
memory: 128M
But I want to analyze kernel core of size 50G+.
Now I am unable to do that.
Can you please tell me how much memory it needs to get atleast "bt" information?
thanks,
Seetharam
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15 years
Crash for SLES 10 hangs.
by Alok Kataria
Hi,
I am trying to debug a bug on SLES 10 kernel using crash.
I have the vmlinux and the vmlinux.debug file for the corresponding
kernel but when I try to start crash it hangs while loading the "slab
cache" data.
****
crash 4.0-7.2.3.el5_3.1
....
....
GNU gdb 6.1
....
This GDB was configured as "x86_64-unknown-linux-gnu"...
please wait... (gathering kmem slab cache data)
****
I then ran crash with "-d 99" debugging support.
Looking at the debug data generated from crash, below is the text which
is repeatedly printed by crash.
------
crash: invalid kernel virtual address: 47 type: "kmem_list3 shared"
<readmem: ffff81000f6266c8, KVADDR, "kmem_list3 shared", 8, (ROE|Q), 7fff89fb1f00>
<readmem: f88948c3c0310006, KVADDR, "shared array_cache limit", 4, (ROE|Q), 7fff89fb1f0c>
crash: invalid kernel virtual address: f88948c3c0310006 type: "shared array_cache limit"
FREEBUF(1)
<readmem: ffff81000f5ab1a0, KVADDR, "kmem_cache_s buffer", 1648, (ROE), a5a480>
<readmem: ffff81000f5ab1a0, KVADDR, "array cache array", 1024, (ROE), 7fff89fb1f10>
GETBUF(512 -> 1)
<readmem: ffff81000f5ab5b0, KVADDR, "array nodelist array", 512, (ROE), a57c80>
<readmem: 47, KVADDR, "kmem_list3 shared", 8, (ROE|Q), 7fff89fb1f00>
crash: invalid kernel virtual address: 47 type: "kmem_list3 shared"
<readmem: 47, KVADDR, "kmem_list3 shared", 8, (ROE|Q), 7fff89fb1f00>
------
Is there a way to tell crash to skip loading slab data ? Or is this a
known bug with crash on sles 10 ?
Please let me know what might be going wrong here.
Thanks,
Alok
15 years
Re: [Crash-utility] Crash for SLES 10 hangs.
by Dave Anderson
----- "Alok Kataria" <akataria(a)vmware.com> wrote:
> Hi,
>
> I am trying to debug a bug on SLES 10 kernel using crash.
> I have the vmlinux and the vmlinux.debug file for the corresponding
> kernel but when I try to start crash it hangs while loading the "slab
> cache" data.
> ****
> crash 4.0-7.2.3.el5_3.1
> ....
> ....
> GNU gdb 6.1
> ....
> This GDB was configured as "x86_64-unknown-linux-gnu"...
>
> please wait... (gathering kmem slab cache data)
> ****
>
> I then ran crash with "-d 99" debugging support.
> Looking at the debug data generated from crash, below is the text which
> is repeatedly printed by crash.
>
> ------
> crash: invalid kernel virtual address: 47 type: "kmem_list3 shared"
> <readmem: ffff81000f6266c8, KVADDR, "kmem_list3 shared", 8, (ROE|Q), 7fff89fb1f00>
> <readmem: f88948c3c0310006, KVADDR, "shared array_cache limit", 4, (ROE|Q), 7fff89fb1f0c>
>
> crash: invalid kernel virtual address: f88948c3c0310006 type: "shared array_cache limit"
> FREEBUF(1)
> <readmem: ffff81000f5ab1a0, KVADDR, "kmem_cache_s buffer", 1648, (ROE), a5a480>
> <readmem: ffff81000f5ab1a0, KVADDR, "array cache array", 1024, (ROE), 7fff89fb1f10>
> GETBUF(512 -> 1)
> <readmem: ffff81000f5ab5b0, KVADDR, "array nodelist array", 512, (ROE), a57c80>
> <readmem: 47, KVADDR, "kmem_list3 shared", 8, (ROE|Q), 7fff89fb1f00>
> crash: invalid kernel virtual address: 47 type: "kmem_list3 shared"
> <readmem: 47, KVADDR, "kmem_list3 shared", 8, (ROE|Q), 7fff89fb1f00>
> ------
>
> Is there a way to tell crash to skip loading slab data ? Or is this a
> known bug with crash on sles 10 ?
I can't help you with SLES10 issues, or whether this is a "known bug"
on SLES10, but yes, you can skip the kmem/slab initialization by
putting "--no_kmem_cache" on the command line.
Dave
>
> Please let me know what might be going wrong here.
>
> Thanks,
> Alok
>
> --
> Crash-utility mailing list
> Crash-utility(a)redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility
15 years
