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| author | Andre Przywara <andre.przywara@calxeda.com> | 2013-05-24 15:47:27 +0200 |
|---|---|---|
| committer | Ian Campbell <ian.campbell@citrix.com> | 2013-05-30 09:20:29 +0100 |
| commit | 130645eee340608c12b632535d3f983508348ba1 (patch) | |
| tree | 21797a241726ed079f4bdc8d06aac587ccef5138 /docs | |
| parent | b68346247f74e002ef180403167888a03f488080 (diff) | |
| download | xen-130645eee340608c12b632535d3f983508348ba1.tar.gz xen-130645eee340608c12b632535d3f983508348ba1.tar.bz2 xen-130645eee340608c12b632535d3f983508348ba1.zip | |
arm/early-printk: allow skipping of UART init
While it seems obvious to initialize the UART before using it, chances
are that some firmware code or the bootloader already did this.
So it may actually be a good idea to skip the initialization, in fact
this fixes early printk on my TC2 Versatile Express.
So provide an option in xen/arch/arm/Rules.mk to only initialize the
UART when needed.
Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/misc/arm/early-printk.txt | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt index 10c30531f6..965add56b8 100644 --- a/docs/misc/arm/early-printk.txt +++ b/docs/misc/arm/early-printk.txt @@ -14,5 +14,9 @@ where mach is the name of the machine: The baud rate is hardcoded in xen/arch/arm/Rules.mk, see there when adding support for new machines. +If not explicitly requested with "EARLY_PRINTK_INIT_UART := y" in Rules.mk, +the code will not try to initialize the UART, so that bootloader or +firmware settings can be used for maximum compatibility. The baud rate +parameter is ignored in this case. By default early printk is disabled. |