Serial Over Lan (SOL) no login prompt on Linux IRQ mode

Paul Fertser fercerpav at
Tue Jul 27 19:30:15 AEST 2021

On Tue, Jul 27, 2021 at 11:53:57AM +0300, Konstantin Klubnichkin wrote:
> SIRQ polarity is something I didn't try, will do it. And yes, SIRQ bit is zero,
> but all other bits are also zero in that register, that confuses me.

I was also able to manually export the SIRQ pin via sysfs and when
manually toggling it the host was seeing UART interrupts and getting
data to and from VUART. That lead nowhere though, so we resorted to
hardware routing in ast2500 between "real UARTs".

> Instead I configure UART routing by direct writing to registers via /dev/mem
> (yes, I know that it's a bad practive, but it's development).

Should work the same.

> With the routing I have absolutely no data in BMC UARTs neither during POST nor
> is OS.
> What I'm missing is how that routing works. Is it on-crystal or UART need to be
> routed to SoC pins thus TX/RX are connected via pins?

With the configuration as shown the host is sending data to and from
"COM1" (0x3f8,4) and any program on BMC is able to interact with it
via /dev/ttyS2, without any additional hardware connections, all
purely in software, the routing happens inside aspeed. Do not forget
to enable ttyS2 in your board's DTS. VUART is not involved at all.

Be free, use free ( software!
mailto:fercerpav at

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