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From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Fabrizio Castro <fabrizio.castro@bp.renesas.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Nicolas Pitre <nico@fluxnic.net>
Subject: Re: [PATCH] ARM: compress: Fix the debug prints
Date: Sun, 9 Aug 2020 22:00:48 +0100	[thread overview]
Message-ID: <20200809210048.GJ1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <CACRpkdaj+YTwk51+1vjFAWbe8y6wrsbrScMoeASnD7U5V2Ky4w@mail.gmail.com>

On Sun, Aug 09, 2020 at 10:49:01PM +0200, Linus Walleij wrote:
> This comes from commit 3b4af9bc2447
> "ARM: 7672/1: uncompress debug support for multiplatform build"
> I think we were just lucky that many kernels were using e.g.
> PL01x and the 8250 users on multiplatform have been scratching
> their head and wondered why the can't turn on
> CONFIG_DEBUG_UNCOMPRESS.

Yep, it has been useful in the distant past when debugging the kernel at
a very low level to be able to "pause" the kernel, or to guarantee that
we grab all messages (using hardware flow control).  However, I suspect
we don't actually need that facility anymore.

> I think it mostly works, but I was baffled that I didn't get the debug
> prints on this Qualcomm platforms, while the "Uncompressing Linux..."
> message was working fine. Adding this made it work.

I suspect on most platforms, the messages generally fit within the
FIFO at the rate we poke the characters in vs the rate they appear
on the serial line.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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      reply	other threads:[~2020-08-09 21:05 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-07 12:26 [PATCH] ARM: compress: Fix the debug prints Linus Walleij
2020-08-07 12:59 ` Russell King - ARM Linux admin
2020-08-09 20:49   ` Linus Walleij
2020-08-09 21:00     ` Russell King - ARM Linux admin [this message]

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