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Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested |
Date: |
Wed, 22 Apr 2015 10:52:51 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 |
On 04/22/15 10:09, Gerd Hoffmann wrote:
> Hi,
>
>> tseg is just normal ram (yes, located at the end of memory), but (once
>> tseg is enabled) only cpus in smm mode are allowed to access it.
>> Likewise busmaster dma access is rejected, so non-smm code can't use the
>> sata controller to access this indirectly.
>
> Update: Seems tseg can be anywhere, there is a "tseg memory base"
> register @ 0xac in pci config space.
>
> Placing it at the end of memory is just what the bios is supposed to do
> by default. And it makes sense to place it there.
>
> <quote>
> This register contains the base address of TSEG DRAM memory. BIOS
> determines the base of TSEG memory by subtracting the TSEG size (PCI
> Device 0, offset 9Eh, bits 2:1) from graphics GTT stolen base (PCI
> Device 0, offset A8h, bits 31:20).
>
> Once D_LCK has been set, these bits becomes read only.
> </quote>
>
> "GTT stolen base" equals "top of below-4g memory" for us because we
> emulate the chipset variant without graphics in qemu.
Thanks, that sounds good. So, as far as I understand, no changes to what
we've discussed thus far.
But, I have another question -- am I allowed to use "top of below-4g
memory" directly, as discussed earlier, or should I use the above PCI
registers? The tseg size will actually come from me (because I'll select
it), but the top I could take from "top of below-4g memory" (preferably,
see earlier), or reading the 0xA8 register.
Unless, of course 0xA8 won't be implemented at all, *because* "we
emulate the chipset variant without graphics in qemu." In other words,
if the 0xA8 register is dependent on the integrated graphics, then I
don't have a question. :)
Thanks!
Laszlo
- Re: [Qemu-devel] [PATCH 2/6] add SMRAM+ESMRAMC wmask, (continued)
- [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Gerd Hoffmann, 2015/04/20
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Paolo Bonzini, 2015/04/20
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Laszlo Ersek, 2015/04/21
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Gerd Hoffmann, 2015/04/21
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Paolo Bonzini, 2015/04/21
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Gerd Hoffmann, 2015/04/21
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Laszlo Ersek, 2015/04/21
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Gerd Hoffmann, 2015/04/22
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Gerd Hoffmann, 2015/04/22
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested,
Laszlo Ersek <=
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Gerd Hoffmann, 2015/04/22
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Laszlo Ersek, 2015/04/22
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Laszlo Ersek, 2015/04/22
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Gerd Hoffmann, 2015/04/23
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Laszlo Ersek, 2015/04/23
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Laszlo Ersek, 2015/04/23
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Gerd Hoffmann, 2015/04/23
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Laszlo Ersek, 2015/04/23
- Re: [Qemu-devel] [PATCH 5/6] [wip] tseg, part1, not (yet) tested, Paolo Bonzini, 2015/04/23
[Qemu-devel] [PATCH 6/6] [wip] tseg, part2, not (yet) tested, Gerd Hoffmann, 2015/04/20