From: Gerd Hoffmann <kraxel@redhat.com>
To: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Cc: vineshp@xilinx.com, peter.maydell@linaro.org,
qemu-devel@nongnu.org, john.williams@xilinx.com,
edgar.iglesias@gmail.com, afaerber@suse.de
Subject: Re: [Qemu-devel] [PATCH v2 11/11] usb/ehci: Put RAM in undefined MMIO regions
Date: Fri, 26 Oct 2012 14:36:07 +0200 [thread overview]
Message-ID: <508A83B7.8050401@redhat.com> (raw)
In-Reply-To: <0c11f3611c74b87c53cfff65ea24f8d6ec82f666.1351229557.git.peter.crosthwaite@xilinx.com>
On 10/26/12 07:47, Peter Crosthwaite wrote:
> Just put RAM regions in the unimplemented spaces in the MMIO region. These
> regions have undefined behaviour, but this at least stops QEMU from segfaulting
> when the guest bangs on these registers (and sucessfully fakes reading and
> writing the registers with no side effects).
Make that an io region, have the read() handler return 0xff, write
handler do nothing except maybe logging/tracing the access for debugging
purposes. That is more correct for unassigned mmio space than backing
by memory. Adding memory also breaks migration btw.
I somehow still think this should be handled one layer up (i.e. the
parent region) which could do the approximate arch-specific action.
Any chance the access you are seeing is at offset 0x68?
cheers,
Gerd
next prev parent reply other threads:[~2012-10-26 12:36 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-26 5:47 [Qemu-devel] [PATCH v2 00/11] Sysbus EHCI + Zynq USB Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 01/11] dma: Define dma_context_memory and use in sysbus-ohci Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 02/11] usb/ehci: Use class_data to init PCI variations Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 03/11] usb/ehci: parameterise the register region offsets Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 04/11] usb/ehci: Abstract away PCI DMA API Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 05/11] usb/ehci: seperate out PCIisms Peter Crosthwaite
2012-10-26 12:24 ` Gerd Hoffmann
2012-10-27 0:32 ` Peter Crosthwaite
2012-10-29 1:04 ` Peter Crosthwaite
2012-10-29 7:43 ` Gerd Hoffmann
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 06/11] usb/ehci: Add Sysbus Infrastructure Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 07/11] usb/ehci: Add Xilinx ps7 USB controller Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 08/11] xilinx_zynq: add USB controllers Peter Crosthwaite
2012-10-26 12:26 ` Gerd Hoffmann
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 09/11] usb/ehci: Guard definition of EHCI_DEBUG Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 10/11] usb/ehci: Debug mode compile fixes Peter Crosthwaite
2012-10-26 5:47 ` [Qemu-devel] [PATCH v2 11/11] usb/ehci: Put RAM in undefined MMIO regions Peter Crosthwaite
2012-10-26 8:37 ` Peter Maydell
2012-10-26 12:36 ` Gerd Hoffmann [this message]
2012-10-26 12:39 ` Peter Maydell
2012-10-27 16:08 ` Peter Crosthwaite
2012-10-27 0:42 ` Peter Crosthwaite
2012-10-29 7:44 ` Gerd Hoffmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=508A83B7.8050401@redhat.com \
--to=kraxel@redhat.com \
--cc=afaerber@suse.de \
--cc=edgar.iglesias@gmail.com \
--cc=john.williams@xilinx.com \
--cc=peter.crosthwaite@xilinx.com \
--cc=peter.maydell@linaro.org \
--cc=qemu-devel@nongnu.org \
--cc=vineshp@xilinx.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).