On Thu 2025-10-16 11:47:53, Marcos Paulo de Souza wrote:
> In v6 the patches were rebased on top of v6.18-rc1, added Reviewed-by tags
> from
> John and did some small changes suggested by him as well.
>
> As usual, how I tested the changes:
>
> Testing
> -------
>
> I did the tests using qemu and reapplying commit f79b163c4231
> ('Revert "serial: 8250: Switch to nbcon console"') created originally by
> John, just to exercise the common 8250 serial from qemu. The commit can
> be checked on [1]. I had to solve some conflicts since the code has been
> reworked after the commit was reverted.
>
> Then I would create three different serial entries on qemu:
> -serial mon:stdio -serial pty -serial pty
>
> And for the kernel command line I added:
> earlyprintk=serial,ttyS2 console=ttyS2 console=ttyS1 console=ttyS1
> kgdboc=ttyS1,115200
>
> Without the last patch on this patchset, when KDB is triggered, the mirroring
> only worked on the earlyprintk console, since it's using the legacy console.
>
> With the last patch applied, KDB mirroring works on legacy and nbcon
> console. For debugging I added some messages to be printed by KDB, showing
> also the console->name and console->index, and I was able to see both
> ->write and ->write_atomic being called, and it all working together.
>
> [1]:
> https://github.com/marcosps/linux/commit/618bd49f8533db85d9c322f9ad1cb0da22aca9ee
> [2]:
> https://lore.kernel.org/lkml/[email protected]/
>
> Signed-off-by: Marcos Paulo de Souza <[email protected]>
> ---
> Changes in v6:
> - Rebased on top opf v6.18-rc1
> - Changed some includes, as suggedted by John
> - Reworked comments as suggested by John
>
> Changes in v5:
> - Added review tags from Petr
> - Changes the way we detect if a CPU is running KDB.
> - Link to v4:
> https://lore.kernel.org/r/[email protected]
>
> Changes in v4:
> - Added ifdefs to only check for KGDB if KGDB was enabled, suggested by John
> Ogness
> - Updated comments about KDB on acquire_direct, suggested by Petr and John
> - Added a new patch to export nbcon_write_context_set_buf, suggested by Petr
> and John
> - Link to v3:
> https://lore.kernel.org/r/[email protected]
>
> Changes in v3:
> - Only call nbcon_context_release if nbcon_context_exit_unsafe returns true
> (John Ogness)
> - Dropped the prototype of console_is_usable from kernel/printk/internal.
> (Petr Mladek)
> - Add comments to the new functions introduced (Petr Mladek)
> - Flush KDB console on nbcon_kdb_release (Petr Mladek)
> - Add an exception for KDB on nbcon_context_try_acquire_direct (John Ogness
> and Petr Mladek)
> - Link to v2:
> https://lore.kernel.org/r/[email protected]
>
> Changes in v2:
> - Set by mistake ..
> - Link to v1:
> https://lore.kernel.org/r/[email protected]
>
> ---
> Marcos Paulo de Souza (5):
> printk: nbcon: Export console_is_usable
> printk: nbcon: Introduce KDB helpers
> printk: nbcon: Allow KDB to acquire the NBCON context
> printk: nbcon: Export nbcon_write_context_set_buf
> kdb: Adapt kdb_msg_write to work with NBCON consoles
>
> include/linux/console.h | 55 ++++++++++++++++++++++++++++++++++++
> include/linux/kdb.h | 16 +++++++++++
> kernel/debug/kdb/kdb_io.c | 47 +++++++++++++++++++++----------
> kernel/printk/internal.h | 45 ------------------------------
> kernel/printk/nbcon.c | 71
> +++++++++++++++++++++++++++++++++++++++++++++--
> 5 files changed, 171 insertions(+), 63 deletions(-)
With the two below compilation fixes, the series seems to be ready for
linux-next.
I am going to wait with pushing a week or so to give other printk and
kdb maintainers and reviewers a chance to look at it.
The following two changes are needed to fix build with
CONFIG_PRINTK and/or CONFIG_KGDB_KDB disabled. I am going
to do the in the respective patches when committing:
diff --git a/include/linux/console.h b/include/linux/console.h
index 81d2c247c01f..690a5f698a5c 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -664,7 +664,7 @@ static inline bool nbcon_exit_unsafe(struct
nbcon_write_context *wctxt) { return
static inline void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt) { }
static inline bool nbcon_kdb_try_acquire(struct console *con,
struct nbcon_write_context *wctxt) {
return false; }
-static inline void nbcon_kdb_release(struct console *con) { }
+static inline void nbcon_kdb_release(struct nbcon_write_context *wctxt) { }
static inline bool console_is_usable(struct console *con, short flags,
bool use_atomic) { return false; }
#endif
diff --git a/include/linux/kdb.h b/include/linux/kdb.h
index db9d73b12a1a..741c58e86431 100644
--- a/include/linux/kdb.h
+++ b/include/linux/kdb.h
@@ -226,7 +226,7 @@ static inline void kdb_init(int level) {}
static inline int kdb_register(kdbtab_t *cmd) { return 0; }
static inline void kdb_unregister(kdbtab_t *cmd) {}
-static inline bool kdb_printf_on_this_cpu(void) { return false };
+static inline bool kdb_printf_on_this_cpu(void) { return false; }
#endif /* CONFIG_KGDB_KDB */
enum {
Best Regards,
Petr
> ---
> base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
> change-id: 20250713-nbcon-kgdboc-efcfc37fde46
>
> Best regards,
> --
> Marcos Paulo de Souza <[email protected]>
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