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riscvarchive / riscv-linux

RISC-V Linux Port
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Earlycon mmio #36

Closed zizztux closed 8 years ago

zizztux commented 8 years ago

Hi.

I add some code that enable fixed-mapping to use ioremap function before kernel mm subsystem is initialized. It is useful to output early-printk into mmio-based UART device.

please, review this code with commit log.

terpstra commented 8 years ago

Hi. Sorry it has taken so long to get to this PR.

The SBI console is the only console we should be using at boot as it is defined in the RISCV platform specification. The hardware behind the SBI calls are still able to be implemented however a designer pleases, so there is no need to write a special driver in the kernel. In fact, this would be undesirable as you cannot retarget that console from the 'bios'.

Only x86 and arm use fixed mappings and AFAICT we should not need them.

Therefore, I am going to close this PR without merging it. Thanks for your PR nevertheless!