lists.openwall.net   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  linux-cve-announce  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]
Message-ID: <20170122090423.GA15061@gmail.com>
Date:   Sun, 22 Jan 2017 10:04:23 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, tglx@...utronix.de,
        peterz@...radead.org, linux-usb@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/4] usb: dbc: early driver for xhci debug capability


* Lu Baolu <baolu.lu@...ux.intel.com> wrote:

> >
> >> +static void xdbc_runtime_delay(unsigned long count)
> >> +{
> >> +	udelay(count);
> >> +}
> >> +static void (*xdbc_delay)(unsigned long) = xdbc_early_delay;
> > Is this udelay() complication really necessary? udelay() should work fine even in 
> > early code. It might not be precisely calibrated, but should be good enough.
> 
> I tried udelay() in the early code. It's not precise enough for the
> hardware handshaking.

Possibly because on x86 early udelay() did not work at all - i.e. there's no delay 
whatsoever.

Could you try it on top of this commit in tip:timers/core:

  4c45c5167c95 x86/timer: Make delay() work during early bootup

?

Thanks,

	Ingo

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ