Re: serial console on Mikrotik RB532 non-working

[Waldemar Brodkorb <wbx@openadk.org>]

Hi Jiaxun,
Jiaxun Yang wrote,
> 
> On Tue, 3 Feb 2026, at 3:24 PM, Jiaxun Yang wrote:
> > On Sun, 1 Feb 2026, at 6:39 PM, Waldemar Brodkorb wrote:
> >> Hi MIPS hackers,
> >>
> >> I want to use the latest Linux kernel on my Mikrotik RB532, but the
> >> serial console is non working. I bisected the problem and the first
> >> breaking change is this commit:
> >
> > Hi,
> >
> > Can you try this?
> 
> Oops sorry I missed a flag, it should be:
> 
> diff --git a/arch/mips/rb532/devices.c b/arch/mips/rb532/devices.c
> index 8ecb56be81ac..239018540221 100644
> --- a/arch/mips/rb532/devices.c
> +++ b/arch/mips/rb532/devices.c
> @@ -213,11 +213,12 @@ static struct platform_device rb532_wdt = {
>  static struct plat_serial8250_port rb532_uart_res[] = {
>         {
>                 .type           = PORT_16550A,
> -               .membase        = (char *)KSEG1ADDR(REGBASE + UART0BASE),
> +               .mapbase        = REGBASE + UART0BASE,
> +               .mapsize        = SZ_4K,
>                 .irq            = UART0_IRQ,
>                 .regshift       = 2,
>                 .iotype         = UPIO_MEM,
> -               .flags          = UPF_BOOT_AUTOCONF,
> +               .flags          = UPF_BOOT_AUTOCONF | UPF_IOREMAP,
>         },
>         {
>                 .flags          = 0,
> 

I tried the patch, but it still hangs here:

RouterBOOT booter 2.18

RouterBoard 532

CPU frequency: 399 MHz
  Memory size:  32 MB

Press any key within 3 seconds to enter setup...
trying dhcp protocol... OK
resolved mac address 9C:BF:0D:00:D6:4E
Gateway: 192.168.1.254
transfer started ........................................ transfer ok, time=525.70s
setting up elf image... OK
jumping to kernel code

Nothing in tcpdump tries to mount nfs, so I believe serial console
breakage is not the only problem here.

Thanks for the help,
 best regards
   Waldemar