lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 7 Dec 2007 16:04:39 +0000
From:	Alan Cox <>
To:	Andi Kleen <>
Cc:	"David P. Reed" <>,,
	Thomas Gleixner <>,
	Ingo Molnar <>,
	"H. Peter Anvin" <>
Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64
 with MCP51 laptops

> modern CPU compared to the bus. But the delay really needs to be something
> that is about IO port speed. Ok in theory you could try to measure
> a outb using RDTSC and then use udelay, but first you would need

You don't need to. Port 0x80 historically is about 8uS so just udelay(8)
and make sure the initial default delay is conservative enough before the
CPU speed is computed.

0x80 should be fine for anything PC compatible anyway, its specifically
reserved as a debug port and supported for *exactly* that purpose by
many chipsets.

The afflicted laptop should really be taken up with the vendor. If its
got port 0x80 wrong gods knows what else it might have problems with.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists