[PATCH] vmcoreinfo: make hwerr_data visible for debugging

[PATCH] vmcoreinfo: make hwerr_data visible for debugging

[Breno Leitao]

If the kernel is compiled with LTO, hwerr_data symbol might be lost, and
vmcoreinfo doesn't have it dumped. This is currently seen in some
production kernels with LTO enabled.

Remove the static qualifier from hwerr_data so that the information is
still preserved when the kernel is built with LTO. Making hwerr_data
a global symbol ensures its debug info survives the LTO link process and
appears in kallsyms.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 kernel/vmcore_info.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/vmcore_info.c b/kernel/vmcore_info.c
index 22b3205dd4dc5..1f42818f77cef 100644
--- a/kernel/vmcore_info.c
+++ b/kernel/vmcore_info.c
@@ -36,7 +36,7 @@ struct hwerr_info {
 	time64_t timestamp;
 };
 
-static struct hwerr_info hwerr_data[HWERR_RECOV_MAX];
+struct hwerr_info hwerr_data[HWERR_RECOV_MAX];
 
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len)

---
base-commit: 053966c344dbd346e71305f530e91ea77916189f
change-id: 20260121-fix_vmcoreinfo-01592f705a77

Best regards,
--  
Breno Leitao <leitao@debian.org>

Re: [PATCH] vmcoreinfo: make hwerr_data visible for debugging

[Andrew Morton]

On Wed, 21 Jan 2026 03:05:44 -0800 Breno Leitao <leitao@debian.org> wrote:

> If the kernel is compiled with LTO, hwerr_data symbol might be lost, and
> vmcoreinfo doesn't have it dumped. This is currently seen in some
> production kernels with LTO enabled.
> 
> Remove the static qualifier from hwerr_data so that the information is
> still preserved when the kernel is built with LTO. Making hwerr_data
> a global symbol ensures its debug info survives the LTO link process and
> appears in kallsyms.
> 
> --- a/kernel/vmcore_info.c
> +++ b/kernel/vmcore_info.c
> @@ -36,7 +36,7 @@ struct hwerr_info {
>  	time64_t timestamp;
>  };
>  
> -static struct hwerr_info hwerr_data[HWERR_RECOV_MAX];
> +struct hwerr_info hwerr_data[HWERR_RECOV_MAX];
>  
>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len)
> 

A non-static symbol which has no external references will be made
static again by those who like to send in little fixups.  A comment
will help prevent that.  How's this?


--- a/kernel/vmcore_info.c~vmcoreinfo-make-hwerr_data-visible-for-debugging-fix
+++ a/kernel/vmcore_info.c
@@ -36,6 +36,7 @@ struct hwerr_info {
 	time64_t timestamp;
 };
 
+/* hwerr_data[] has global scope to make it available in vmcoreinfo under LTO */
 struct hwerr_info hwerr_data[HWERR_RECOV_MAX];
 
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
_

Re: [PATCH] vmcoreinfo: make hwerr_data visible for debugging

[Breno Leitao]

Hello Andrew,

On Wed, Jan 21, 2026 at 12:27:47PM -0800, Andrew Morton wrote:
> On Wed, 21 Jan 2026 03:05:44 -0800 Breno Leitao <leitao@debian.org> wrote:
> 
> > If the kernel is compiled with LTO, hwerr_data symbol might be lost, and
> > vmcoreinfo doesn't have it dumped. This is currently seen in some
> > production kernels with LTO enabled.
> > 
> > Remove the static qualifier from hwerr_data so that the information is
> > still preserved when the kernel is built with LTO. Making hwerr_data
> > a global symbol ensures its debug info survives the LTO link process and
> > appears in kallsyms.
> > 
> > --- a/kernel/vmcore_info.c
> > +++ b/kernel/vmcore_info.c
> > @@ -36,7 +36,7 @@ struct hwerr_info {
> >  	time64_t timestamp;
> >  };
> >  
> > -static struct hwerr_info hwerr_data[HWERR_RECOV_MAX];
> > +struct hwerr_info hwerr_data[HWERR_RECOV_MAX];
> >  
> >  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
> >  			  void *data, size_t data_len)
> > 
> 
> A non-static symbol which has no external references will be made
> static again by those who like to send in little fixups.  A comment
> will help prevent that.  How's this?

very good point, I will update.

Thanks
--breno