On Mon, Jan 9, 2023 at 4:28 PM Alistair Francis <alistai...@gmail.com> wrote:
> On Tue, Jan 10, 2023 at 1:47 AM Oleksii Kurochko > <oleksii.kuroc...@gmail.com> wrote: > > > > The patch introduces a basic stuff of early_printk functionality > > which will be enough to print 'hello from C environment". > > early_printk() function was changed in comparison with original as > > common isn't being built now so there is no vscnprintf. > > > > Because printk() relies on a serial driver (like the ns16550 driver) > > and drivers require working virtual memory (ioremap()) there is not > > print functionality early in Xen boot. > > > > This commit adds early printk implementation built on the putc SBI call. > > > > As sbi_console_putchar() is being already planned for deprecation > > it is used temporary now and will be removed or reworked after > > real uart will be ready. > > There was a discussion to add a new SBI putchar replacement. It > doesn't seem to be completed yet, but there might be an SBI > replacement for this in the future as well. > > Alistair > Are you referring to the Debug Console Extension (EID #0x4442434E "DBCN")”? https://lists.riscv.org/g/tech-prs/topic/96051183#84 Best, Bobby > > > > Signed-off-by: Bobby Eshleman <bobby.eshle...@gmail.com> > > Signed-off-by: Oleksii Kurochko <oleksii.kuroc...@gmail.com> > > --- > > Changes in V2: > > - add license to early_printk.c > > - add signed-off-by Bobby > > - add RISCV_32 to Kconfig.debug to EARLY_PRINTK config > > - update commit message > > - order the files alphabetically in Makefile > > --- > > xen/arch/riscv/Kconfig.debug | 7 +++++ > > xen/arch/riscv/Makefile | 1 + > > xen/arch/riscv/early_printk.c | 33 +++++++++++++++++++++++ > > xen/arch/riscv/include/asm/early_printk.h | 12 +++++++++ > > 4 files changed, 53 insertions(+) > > create mode 100644 xen/arch/riscv/early_printk.c > > create mode 100644 xen/arch/riscv/include/asm/early_printk.h > > > > diff --git a/xen/arch/riscv/Kconfig.debug b/xen/arch/riscv/Kconfig.debug > > index e69de29bb2..6ba0bd1e5a 100644 > > --- a/xen/arch/riscv/Kconfig.debug > > +++ b/xen/arch/riscv/Kconfig.debug > > @@ -0,0 +1,7 @@ > > +config EARLY_PRINTK > > + bool "Enable early printk config" > > + default DEBUG > > + depends on RISCV_64 || RISCV_32 > > + help > > + > > + Enables early printk debug messages > > diff --git a/xen/arch/riscv/Makefile b/xen/arch/riscv/Makefile > > index fd916e1004..1a4f1a6015 100644 > > --- a/xen/arch/riscv/Makefile > > +++ b/xen/arch/riscv/Makefile > > @@ -1,3 +1,4 @@ > > +obj-$(CONFIG_EARLY_PRINTK) += early_printk.o > > obj-$(CONFIG_RISCV_64) += riscv64/ > > obj-y += sbi.o > > obj-y += setup.o > > diff --git a/xen/arch/riscv/early_printk.c > b/xen/arch/riscv/early_printk.c > > new file mode 100644 > > index 0000000000..88da5169ed > > --- /dev/null > > +++ b/xen/arch/riscv/early_printk.c > > @@ -0,0 +1,33 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > +/* > > + * RISC-V early printk using SBI > > + * > > + * Copyright (C) 2021 Bobby Eshleman <bobbyeshle...@gmail.com> > > + */ > > +#include <asm/sbi.h> > > +#include <asm/early_printk.h> > > + > > +/* > > + * TODO: > > + * sbi_console_putchar is already planned for deprication > > + * so it should be reworked to use UART directly. > > +*/ > > +void early_puts(const char *s, size_t nr) > > +{ > > + while ( nr-- > 0 ) > > + { > > + if (*s == '\n') > > + sbi_console_putchar('\r'); > > + sbi_console_putchar(*s); > > + s++; > > + } > > +} > > + > > +void early_printk(const char *str) > > +{ > > + while (*str) > > + { > > + early_puts(str, 1); > > + str++; > > + } > > +} > > diff --git a/xen/arch/riscv/include/asm/early_printk.h > b/xen/arch/riscv/include/asm/early_printk.h > > new file mode 100644 > > index 0000000000..05106e160d > > --- /dev/null > > +++ b/xen/arch/riscv/include/asm/early_printk.h > > @@ -0,0 +1,12 @@ > > +#ifndef __EARLY_PRINTK_H__ > > +#define __EARLY_PRINTK_H__ > > + > > +#include <xen/early_printk.h> > > + > > +#ifdef CONFIG_EARLY_PRINTK > > +void early_printk(const char *str); > > +#else > > +static inline void early_printk(const char *s) {}; > > +#endif > > + > > +#endif /* __EARLY_PRINTK_H__ */ > > -- > > 2.38.1 > > > > >
