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Re: [Qemu-devel] [PATCH] 64 bit I/O support v7
From: |
Blue Swirl |
Subject: |
Re: [Qemu-devel] [PATCH] 64 bit I/O support v7 |
Date: |
Sat, 2 May 2009 18:23:42 +0300 |
On 5/2/09, Paul Brook <address@hidden> wrote:
> > Should a new intermediate bus layer also do byte swapping?
>
>
> Yes, though a bus layer isn't actually a necessary prerequisite.
>
> As I mentioned in the recent "Smarter compilation for target devices"
> thread[1], having individual devices do byteswapping is bogus. A while ago I
> reworked the TLB handling, so there should now be spare bits that can be used
> for things like byteswapping.
This version does the byte swapping and width translation in exec.c.
Sparc32 OpenBIOS/Linux does not use the wrong sized accesses, so that
part may be untested.
Some problems:
- Small writes cause a read-modify-write cycle, but I think that may
happen with real devices too. Another solution is to write zero in
other byte lanes without reading.
- The LE/BE distinction does not seem to be very obvious for devices.
I think the board should give the is_le value to the device.
- There is a small performance hit for the native access case. This
could be avoided by extending io_mem_opaque to cover all sizes.
Emulate_non_native_widths.patch
Description: application/mbox
Use_new_registration_functions.patch
Description: application/mbox
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, (continued)
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Paul Brook, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Robert Reif, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Paul Brook, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Blue Swirl, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Edgar E. Iglesias, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Robert Reif, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Robert Reif, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Paul Brook, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Robert Reif, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Paul Brook, 2009/05/01
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7,
Blue Swirl <=
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Paul Brook, 2009/05/02
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Jamie Lokier, 2009/05/04
- Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Edgar E. Iglesias, 2009/05/05
Re: [Qemu-devel] [PATCH] 64 bit I/O support v7, Robert Reif, 2009/05/01