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Re: [PATCH 2/5] hw/arm/aspeed: Select console UART from machine
From: |
Andrew Jeffery |
Subject: |
Re: [PATCH 2/5] hw/arm/aspeed: Select console UART from machine |
Date: |
Tue, 31 Aug 2021 20:53:10 +0930 |
User-agent: |
Cyrus-JMAP/3.5.0-alpha0-1124-g8f1c7cb9de-fm-20210824.001-g8f1c7cb9 |
Hi Cédric, Peter,
On Tue, 31 Aug 2021, at 20:09, Cédric Le Goater wrote:
> On 8/28/21 5:58 PM, Peter Delevoryas wrote:
> > I think I’m a little confused on this part. What I meant by “most machines
> > just use UART5” was that most DTS’s use “stdout-path=&uart5”, but fuji uses
> > “stdout-path=&uart1”. I /do/ see that SCU510 includes a bit related to
> > UART, but it’s for disabling booting from UART1 and UART5. I just care
> > about the console aspect, not booting.
>
> The UART can be switched with SCU70[29] on the AST2500, btw.
If it helps, neither the AST2600's "Boot from UART" feature nor the
AST2[456]00's "Debug UART" feature are related to which UART is used as
the BMC console by u-boot and/or the kernel - the latter is entirely a
software thing.
The "Debug UART" is a hardware backdoor, a UART-to-AHB bridge
implemented by the SoC. It provides a shell environment that allows you
to issue transactions directly on the AHB if you perform a magic knock.
I have a driver for it implemented here:
https://github.com/amboar/cve-2019-6260/blob/master/src/debug.c
SCU70[29] on the AST2500 selects whether this backdoor is exposed on
UART1 or UART5.
The "Boot from UART" feature is implemented in the AST2600 ROM code as
a fallback for loading the SPL if fetching it from SPI-NOR or the eMMC
fails, or the SPL is incorrectly signed for secure-boot.
I think Peter is on the right track with this patch?
Andrew
- Re: [PATCH 3/5] hw/arm/aspeed: Add fuji machine type, (continued)
[PATCH 2/5] hw/arm/aspeed: Select console UART from machine, pdel, 2021/08/27
Re: [PATCH 2/5] hw/arm/aspeed: Select console UART from machine, Cédric Le Goater, 2021/08/31
Re: [PATCH 2/5] hw/arm/aspeed: Select console UART from machine,
Andrew Jeffery <=
Re: [PATCH 2/5] hw/arm/aspeed: Select console UART from machine, Cédric Le Goater, 2021/08/31
Re: [PATCH 2/5] hw/arm/aspeed: Select console UART from machine, Peter Delevoryas, 2021/08/31
Re: [PATCH 2/5] hw/arm/aspeed: Select console UART from machine, Philippe Mathieu-Daudé, 2021/08/31
Re: [PATCH 2/5] hw/arm/aspeed: Select console UART from machine, Cédric Le Goater, 2021/08/31
[PATCH 5/5] hw/arm/aspeed: Initialize AST2600 clock selection registers, pdel, 2021/08/27
[PATCH 4/5] hw/arm/aspeed: Fix AST2600_CLK_SEL3 address, pdel, 2021/08/27
[PATCH 1/5] hw/arm/aspeed: Add get_irq to AspeedSoCClass, pdel, 2021/08/27