From: Rene Herman <rene.herman@keyaccess.nl>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: 7eggert@gmx.de, Bjorn Helgaas <bjorn.helgaas@hp.com>,
linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
Russell King <rmk+serial@arm.linux.org.uk>,
Jeff Garzik <jeff@garzik.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [patch 2/2] 8250_pnp: register x86 COM ports at the conventional ttyS names
Date: Thu, 17 Jan 2008 00:34:05 +0100 [thread overview]
Message-ID: <478E946D.9040105@keyaccess.nl> (raw)
In-Reply-To: <478E6C20.2030005@zytor.com>
On 16-01-08 21:42, H. Peter Anvin wrote:
> Bodo Eggert wrote:
>>
>> BTW1: These addresses may be used to detect ports on non-standard
>> addresses, but unfortunately they don't tell the IRQ.
>>
>> BTW2: When I submitted a patch using the BIOS data area, I was told
>> that it might not exist on systems booting from non-PC firmware. This
>> claim was not yet backed with any knowledge, nor did anybody suggest a
>> way to detect this situation.
>
> This is, of course, true. It doesn't exactly help that some (most?)
> non-PC firmware at least mimic the BIOS data area.
>
> In this particular case, there is some minor sanity-checking that can be
> done: the values should be nonzero and aligned 8.
The number of places expected to contain something sensible should I believe
first be verified at 0x410 -- the equipment word. Bits 11-9 (0x0e00) should
be the number of serial ports, 0 to 4 (so 5-7 is also a sanity check) and if
BIOSes can be expected to zero out the non-used base-addresses (at 0x400,
0x402, 0x404, 0x406) that's another sanity check. Don't know if they can
though...
Rene.
next prev parent reply other threads:[~2008-01-16 23:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <9MjWa-VI-9@gated-at.bofh.it>
[not found] ` <9MjWb-VI-11@gated-at.bofh.it>
[not found] ` <9MlEG-3Mx-13@gated-at.bofh.it>
[not found] ` <9Mmra-56f-29@gated-at.bofh.it>
2008-01-16 20:33 ` [patch 2/2] 8250_pnp: register x86 COM ports at the conventional ttyS names Bodo Eggert
2008-01-16 20:33 ` Bodo Eggert
2008-01-16 20:42 ` H. Peter Anvin
2008-01-16 23:34 ` Rene Herman [this message]
2008-01-18 18:10 ` H. Peter Anvin
2008-01-16 17:05 [patch 0/2] serial: explicitly request ttyS0-3 for COM1-4 Bjorn Helgaas
2008-01-16 17:05 ` [patch 2/2] 8250_pnp: register x86 COM ports at the conventional ttyS names Bjorn Helgaas
2008-01-16 17:05 ` Bjorn Helgaas
2008-01-16 18:42 ` Russell King
2008-01-16 18:44 ` H. Peter Anvin
2008-01-16 19:47 ` Bjorn Helgaas
2008-01-16 19:49 ` H. Peter Anvin
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