From: Baoquan He <bhe@redhat.com>
To: Hari Bathini <hbathini@linux.ibm.com>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Kexec-ml <kexec@lists.infradead.org>,
lkml <linux-kernel@vger.kernel.org>,
Sourabh Jain <sourabhjain@linux.ibm.com>,
Mahesh J Salgaonkar <mahesh@linux.ibm.com>,
Dave Young <dyoung@redhat.com>
Subject: Re: [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel()
Date: Sun, 3 Sep 2023 11:36:49 +0800 [thread overview]
Message-ID: <ZPP/UeP1zUbGPzrt@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20230901190438.375678-1-hbathini@linux.ibm.com>
Hi Hari,
On 09/02/23 at 12:34am, Hari Bathini wrote:
> Currently, is_kdump_kernel() returns true when elfcorehdr_addr is set.
> While elfcorehdr_addr is set for kexec based kernel dump mechanism,
> alternate dump capturing methods like fadump [1] also set it to export
> the vmcore. is_kdump_kernel() is used to restrict resources in crash
> dump capture kernel but such restrictions may not be desirable for
> fadump. Allow is_kdump_kernel() to be defined differently for such
> scenarios. With this, is_kdump_kernel() could be false while vmcore
> is usable. So, introduce is_crashdump_kernel() to return true when
> elfcorehdr_addr is set and use it for vmcore related checks.
I got what is done in these two patches, but didn't get why they need be
done. vmcore_unusable()/is_vmcore_usable() are only unitilized in ia64.
Why do you care if it's is_crashdump_kernel() or is_kdump_kernel()?
If you want to override the generic is_kdump_kernel() with powerpc's own
is_kdump_kernel(), your below change is enough to allow you to do that.
I can't see why is_crashdump_kernel() is needed. Could you explain that
specifically?
#ifndef is_kdump_kernel
static inline bool is_kdump_kernel(void)
{
return elfcorehdr_addr != ELFCORE_ADDR_MAX;
}
#endif
Thanks
Baoquan
> [1] https://docs.kernel.org/powerpc/firmware-assisted-dump.html
>
> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
> ---
> include/linux/crash_dump.h | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
> index 0f3a656293b0..1052a0faf0dd 100644
> --- a/include/linux/crash_dump.h
> +++ b/include/linux/crash_dump.h
> @@ -50,6 +50,7 @@ void vmcore_cleanup(void);
> #define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
> #endif
>
> +#ifndef is_kdump_kernel
> /*
> * is_kdump_kernel() checks whether this kernel is booting after a panic of
> * previous kernel or not. This is determined by checking if previous kernel
> @@ -64,6 +65,19 @@ static inline bool is_kdump_kernel(void)
> {
> return elfcorehdr_addr != ELFCORE_ADDR_MAX;
> }
> +#endif
> +
> +/*
> + * Return true if this is a dump capture kernel, where vmcore needs to be
> + * exported, irrespective of the dump capture mechanism in use.
> + *
> + * Same as is_kdump_kernel() unless arch specific code defines is_kdump_kernel()
> + * differently while supporting other dump capturing mechanisms.
> + */
> +static inline bool is_crashdump_kernel(void)
> +{
> + return elfcorehdr_addr != ELFCORE_ADDR_MAX;
> +}
>
> /* is_vmcore_usable() checks if the kernel is booting after a panic and
> * the vmcore region is usable.
> @@ -75,7 +89,7 @@ static inline bool is_kdump_kernel(void)
>
> static inline int is_vmcore_usable(void)
> {
> - return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
> + return is_crashdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
> }
>
> /* vmcore_unusable() marks the vmcore as unusable,
> @@ -84,7 +98,7 @@ static inline int is_vmcore_usable(void)
>
> static inline void vmcore_unusable(void)
> {
> - if (is_kdump_kernel())
> + if (is_crashdump_kernel())
> elfcorehdr_addr = ELFCORE_ADDR_ERR;
> }
>
> --
> 2.41.0
>
next prev parent reply other threads:[~2023-09-03 3:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-01 19:04 [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Hari Bathini
2023-09-01 19:04 ` [PATCH 2/2] powerpc/fadump: make is_kdump_kernel() return false when fadump is active Hari Bathini
2023-09-03 3:36 ` Baoquan He [this message]
2023-09-04 14:34 ` [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Hari Bathini
2023-09-05 2:30 ` Baoquan He
2023-09-05 19:25 ` Hari Bathini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZPP/UeP1zUbGPzrt@MiWiFi-R3L-srv \
--to=bhe@redhat.com \
--cc=dyoung@redhat.com \
--cc=hbathini@linux.ibm.com \
--cc=kexec@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mahesh@linux.ibm.com \
--cc=sourabhjain@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).