Thanks Kofi for clarification.
On 31 Oct 2017 4:28 p.m., wrote:
Hi Munees,
Well, seL4 doesn't use U-boot's driver -- rather the ELFloader which loads
the kernel has its own UART driver, and it uses that to print until it
loads the kernel. From there, the kernel also has its own minimal UART
driver, which it uses to print messages (if CONFIG_PRINTING is enabled).
Furthermore, after the kernel drops to userspace, userspace will simply
avoid calling printf() until it's initialized a UART driver. After
userspace has initialized its own UART driver, it will start calling
printf().
So there are actually several UART drivers in play.
--
Kofi Doku Atuah
Kernel engineer
DATA61 | CSIRO
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On 31 Oct 2017 4:28 p.m., wrote:
Hi Munees,
Well, seL4 doesn't use U-boot's driver -- rather the ELFloader which loads
the kernel has its own UART driver, and it uses that to print until it
loads the kernel. From there, the kernel also has its own minimal UART
driver, which it uses to print messages (if CONFIG_PRINTING is enabled).
Furthermore, after the kernel drops to userspace, userspace will simply
avoid calling printf() until it's initialized a UART driver. After
userspace has initialized its own UART driver, it will start calling
printf().
So there are actually several UART drivers in play.
--
Kofi Doku Atuah
Kernel engineer
DATA61 | CSIRO
_______________________________________________
Devel mailing list
Devel@sel4.systems
https://sel4.systems/lists/listinfo/devel