| Message ID | 20250212222157.2974150-1-dmukhin@ford.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | xen/console: make console buffer size configurable | expand |
On Wed, 12 Feb 2025, dmkhn@proton.me wrote: > Add new CONRING_SIZE Kconfig parameter to specify the boot console buffer size > in bytes. The value is rounded to the nearest power of 2 to match existing > conring_size= behavior. > > The supported range is [16KiB..128MiB]. > > Bump default size to 32 KiB. > > Link: https://gitlab.com/xen-project/xen/-/issues/185 > Signed-off-by: Denis Mukhin <dmukhin@ford.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> > --- > Link to the original change: > - https://lore.kernel.org/xen-devel/20250103-vuart-ns8250-v3-v1-15-c5d36b31d66c@ford.com/ > --- > docs/misc/xen-command-line.pandoc | 5 ++++- > xen/drivers/char/Kconfig | 12 ++++++++++++ > xen/drivers/char/console.c | 6 +++--- > 3 files changed, 19 insertions(+), 4 deletions(-) > > diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc > index 9bbd00baef..563cdbdd49 100644 > --- a/docs/misc/xen-command-line.pandoc > +++ b/docs/misc/xen-command-line.pandoc > @@ -425,10 +425,13 @@ The following are examples of correct specifications: > ### conring_size > > `= <size>` > > -> Default: `conring_size=16k` > +> Default: `conring_size=32k` > > Specify the size of the console ring buffer. > > +The console ring buffer size can be selected at build time via > +CONFIG_CONRING_SIZE. > + > ### console > > `= List of [ vga | com1[H,L] | com2[H,L] | pv | dbgp | ehci | xhci | none ]` > > diff --git a/xen/drivers/char/Kconfig b/xen/drivers/char/Kconfig > index e6e12bb413..54a3a79da3 100644 > --- a/xen/drivers/char/Kconfig > +++ b/xen/drivers/char/Kconfig > @@ -96,6 +96,18 @@ config SERIAL_TX_BUFSIZE > > Default value is 32768 (32KiB). > > +config CONRING_SIZE > + int "Console buffer size" > + default 32768 > + range 16384 134217728 > + help > + Select the boot console buffer size (in bytes). > + Note, the value provided will be rounded down to the nearest power of 2. > + Run-time console buffer size is the same as the boot console size, > + unless overridden via 'conring_size=' boot parameter. > + > + Default value is 32768 (32KiB). > + > config XHCI > bool "XHCI DbC UART driver" > depends on X86 > diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c > index ee5f720de4..73d24a7821 100644 > --- a/xen/drivers/char/console.c > +++ b/xen/drivers/char/console.c > @@ -101,12 +101,12 @@ static int cf_check parse_console_timestamps(const char *s); > custom_runtime_param("console_timestamps", parse_console_timestamps, > con_timestamp_mode_upd); > > -/* conring_size: allows a large console ring than default (16kB). */ > +/* conring_size: override build-time CONRING_SIZE setting. */ > static uint32_t __initdata opt_conring_size; > size_param("conring_size", opt_conring_size); > > -#define _CONRING_SIZE 16384 > -#define CONRING_IDX_MASK(i) ((i)&(conring_size-1)) > +#define _CONRING_SIZE (1UL << (31 - __builtin_clz(CONFIG_CONRING_SIZE))) > +#define CONRING_IDX_MASK(i) ((i) & (conring_size - 1)) > static char __initdata _conring[_CONRING_SIZE]; > static char *__read_mostly conring = _conring; > static uint32_t __read_mostly conring_size = _CONRING_SIZE; > -- > 2.34.1 > >
On 12.02.2025 23:31, dmkhn@proton.me wrote: > --- a/xen/drivers/char/Kconfig > +++ b/xen/drivers/char/Kconfig > @@ -96,6 +96,18 @@ config SERIAL_TX_BUFSIZE > > Default value is 32768 (32KiB). > > +config CONRING_SIZE > + int "Console buffer size" > + default 32768 > + range 16384 134217728 > + help > + Select the boot console buffer size (in bytes). Why in bytes when ... > + Note, the value provided will be rounded down to the nearest power of 2. ... this rounding is done anyway? Why have people type in complicated numbers? A granularity of 1k would already be an improvement; yet better would be if this was a power-of-two value altogether. Jan
diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc index 9bbd00baef..563cdbdd49 100644 --- a/docs/misc/xen-command-line.pandoc +++ b/docs/misc/xen-command-line.pandoc @@ -425,10 +425,13 @@ The following are examples of correct specifications: ### conring_size > `= <size>` -> Default: `conring_size=16k` +> Default: `conring_size=32k` Specify the size of the console ring buffer. +The console ring buffer size can be selected at build time via +CONFIG_CONRING_SIZE. + ### console > `= List of [ vga | com1[H,L] | com2[H,L] | pv | dbgp | ehci | xhci | none ]` diff --git a/xen/drivers/char/Kconfig b/xen/drivers/char/Kconfig index e6e12bb413..54a3a79da3 100644 --- a/xen/drivers/char/Kconfig +++ b/xen/drivers/char/Kconfig @@ -96,6 +96,18 @@ config SERIAL_TX_BUFSIZE Default value is 32768 (32KiB). +config CONRING_SIZE + int "Console buffer size" + default 32768 + range 16384 134217728 + help + Select the boot console buffer size (in bytes). + Note, the value provided will be rounded down to the nearest power of 2. + Run-time console buffer size is the same as the boot console size, + unless overridden via 'conring_size=' boot parameter. + + Default value is 32768 (32KiB). + config XHCI bool "XHCI DbC UART driver" depends on X86 diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c index ee5f720de4..73d24a7821 100644 --- a/xen/drivers/char/console.c +++ b/xen/drivers/char/console.c @@ -101,12 +101,12 @@ static int cf_check parse_console_timestamps(const char *s); custom_runtime_param("console_timestamps", parse_console_timestamps, con_timestamp_mode_upd); -/* conring_size: allows a large console ring than default (16kB). */ +/* conring_size: override build-time CONRING_SIZE setting. */ static uint32_t __initdata opt_conring_size; size_param("conring_size", opt_conring_size); -#define _CONRING_SIZE 16384 -#define CONRING_IDX_MASK(i) ((i)&(conring_size-1)) +#define _CONRING_SIZE (1UL << (31 - __builtin_clz(CONFIG_CONRING_SIZE))) +#define CONRING_IDX_MASK(i) ((i) & (conring_size - 1)) static char __initdata _conring[_CONRING_SIZE]; static char *__read_mostly conring = _conring; static uint32_t __read_mostly conring_size = _CONRING_SIZE;
Add new CONRING_SIZE Kconfig parameter to specify the boot console buffer size in bytes. The value is rounded to the nearest power of 2 to match existing conring_size= behavior. The supported range is [16KiB..128MiB]. Bump default size to 32 KiB. Link: https://gitlab.com/xen-project/xen/-/issues/185 Signed-off-by: Denis Mukhin <dmukhin@ford.com> --- Link to the original change: - https://lore.kernel.org/xen-devel/20250103-vuart-ns8250-v3-v1-15-c5d36b31d66c@ford.com/ --- docs/misc/xen-command-line.pandoc | 5 ++++- xen/drivers/char/Kconfig | 12 ++++++++++++ xen/drivers/char/console.c | 6 +++--- 3 files changed, 19 insertions(+), 4 deletions(-)