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Re: [Qemu-devel] [PATCH v3 0/4] SysFS driver for QEMU fw_cfg device
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v3 0/4] SysFS driver for QEMU fw_cfg device |
Date: |
Mon, 5 Oct 2015 13:50:47 +0100 |
On 5 October 2015 at 13:40, Gabriel L. Somlo <address@hidden> wrote:
> In addition, Michael's comment earlier in the thread suggests that
> even my current acpi version isn't sufficiently "orthodox" w.r.t.
> ACPI, and I should be providing the hardware access routine as
> an ACPI/AML routine, to avoid race conditions with the rest of ACPI,
> and for encapsulation. I.e. it's even rude to use the fw_cfg node's
> ACPI _CRS method (the part where I'd be treating it like a DT stand-in
> only to query fw_cfg's hardware specifics).
If you want to try to support "firmware might also be reading
fw_cfg at the same time as the kernel" this is a (painful)
problem regardless of how the kernel figures out whether a
fw_cfg device is present. I had assumed that one of the design
assumptions of this series was that firmware would only
read the fw_cfg before booting the guest kernel and never touch
it afterwards. If it might touch it later then letting the
guest kernel also mess with fw_cfg seems like a really bad idea.
thanks
-- PMM
- Re: [Qemu-devel] [PATCH v3 2/4] firmware: use acpi to detect QEMU fw_cfg device for sysfs fw_cfg driver, (continued)
[Qemu-devel] [PATCH v3 1/4] firmware: introduce sysfs driver for QEMU's fw_cfg device, Gabriel L. Somlo, 2015/10/08
Re: [Qemu-devel] [PATCH v3 0/4] SysFS driver for QEMU fw_cfg device, Mark Rutland, 2015/10/08
Re: [Qemu-devel] [PATCH v3 0/4] SysFS driver for QEMU fw_cfg device, Paolo Bonzini, 2015/10/08
[Qemu-devel] [PATCH v3 4/4] firmware: create directory hierarchy for sysfs fw_cfg entries, Gabriel L. Somlo, 2015/10/08