Hi Simon,
I am looking at the driver-model serial code.
I notice driver-model serial code uses ".data" section
for storing the current device even before relocation.
This code in drivers/serial/serial-uclass.c:
/* The currently-selected console serial device */
struct udevice *cur_dev __attribute__ ((section(".data")));
In my understanding, we should not write any data to
.data section before relocation.
Let's say we are booting U-Boot from NOR flash.
Before relocation, everything (including .data section)
is placed on NOR flash which is read-only.
(Please point out if I am wrong.)
We are only allowed to write data to the stack, gd_t, bd_t
and malloc area (if CONFIG_SYS_MALLOC_F_LEN is defined)
before relocation, I think.
I think that is why pre-driver-model serial uses a hard-coded
default serial port before relocation.
This code in driver/serial/serial.c:
if (!(gd->flags & GD_FLG_RELOC))
dev = default_serial_console();
else if (!serial_current)
dev = default_serial_console();
else
dev = serial_current;
My question is, does printf() work
with driver-model UART and XIP device such NOR flash?
Best Regards
Masahiro Yamada
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