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Date: Thu, 17 Dec 2015 11:09:23 -0500
From: "Gabriel L. Somlo" <somlo@....edu>
To: gregkh@...uxfoundation.org, robh+dt@...nel.org, pawel.moll@....com,
mark.rutland@....com, ijc+devicetree@...lion.org.uk,
galak@...eaurora.org, arnd@...db.de, lersek@...hat.com,
ralf@...ux-mips.org, rmk+kernel@....linux.org.uk, eric@...olt.net,
hanjun.guo@...aro.org, zajec5@...il.com, sudeep.holla@....com,
agross@...eaurora.org, linux-api@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Cc: qemu-devel@...gnu.org, jordan.l.justen@...el.com, mst@...hat.com,
peter.maydell@...aro.org, leif.lindholm@...aro.org,
ard.biesheuvel@...aro.org, pbonzini@...hat.com, kraxel@...hat.com,
luto@...capital.net, stefanha@...il.com, revol@...e.fr,
matt@...eblueprint.co.uk
Subject: Re: [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device
ping ?
Also, for the corresponding patch set on the QEMU end of things,
ping on http://thread.gmane.org/gmane.comp.emulators.qemu/376321
Thanks,
--Gabriel
On Fri, Dec 04, 2015 at 10:29:02AM -0500, Gabriel L. Somlo wrote:
> Allow access to QEMU firmware blobs, passed into the guest VM via
> the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name,
> size, and fw_cfg key), as well as the raw binary blob data may be
> accessed.
>
> The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was
> selected based on overall similarity to the type of information
> exposed under /sys/firmware/dmi/entries/...
>
> New since v5:
>
> - fixed typos in documentation files (Patches 1/4 and 4/4
>
> - printf/scanf type modifier for phys_addr_t now matches
> arch-specific width (u32 vs. u64), avoiding compiler warnings.
> (tested on i386 with and without PAE, and on armv7hl with and
> without lpae -- the latter pair took quite a while on an
> emulated QEMU guest :) )
>
> Thanks,
> --Gabriel
>
> >New since v4:
> >
> > Documentation (Patches 1/4 and 4/4) now points to the authoritative
> > file in the QEMU source tree for any details related to the "hardware
> > interface" of the fw_cfg device; Only details specific to sysfs (1/4)
> > and DT (4/4) should stay in the kernel docs.
> >
> >>New (since v3):
> >>
> >> Patch 1/4: Device probing now works with either ACPI, DT, or
> >> optionally by manually specifying a base, size, and
> >> register offsets on the command line. This way, all
> >> architectures offering fw_cfg can be supported, although
> >> x86 and ARM get *automatic* support via ACPI and/or DT.
> >>
> >> HUGE thanks to Laszlo Ersek <lersek@...hat.com> for
> >> pointing out drivers/virtio/virtio_mmio.c, as an example
> >> on how to pull this off !!!
> >>
> >> Stefan: I saw Marc's DMA patches to fw_cfg. Since only
> >> x86 and ARM will support it starting with QEMU 2.5, and
> >> since I expect to get lots of otherwise interesting (but
> >> otherwise orthogonal) feedback on this series, I'd like
> >> to stick with ioread8() across the board for now. We can
> >> always patch in DMA support in a backward compatible way
> >> later, once this series gets (hopefully) accepted :)
> >>
> >> Patch 2/4: (was 3/4 in v3): unchanged. Exports kset_find_obj() so
> >> modules can call it.
> >>
> >> Patch 3/4: (was 4/4 in v3): rebased, but otherwise the same.
> >> Essentially, creates a "human readable" directory
> >> hierarchy from "path-like" tokens making up fw_cfg
> >> blob names. I'm not really sure there's a way to make
> >> this happen via udev rules, but I have at least one
> >> potential use case for doing it *before* udev becomes
> >> available (cc: Andy Lutomirski <luto@...capital.net>),
> >> so I'd be happy to leave this functionality in the
> >> kernel module. See further below for an illustration
> >> of this.
> >>
> >> Patch 4/4: Updates the existing ARM DT documentation for fw_cfg,
> >> mainly by pointing at the more comprehensive document
> >> introduced with Patch 1/4 for details on the fw_cfg
> >> device interface, leaving only the specific ARM/DT
> >> address/size node information in place.
> >>
> >>> In addition to the "by_key" blob listing, e.g.:
> >>>
> >>> $ tree /sys/firmware/qemu_fw_cfg/
> >>> /sys/firmware/qemu_fw_cfg/
> >>> |-- by_key
> >>> | |-- 32
> >>> | | |-- key
> >>> | | |-- name ("etc/boot-fail-wait")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 33
> >>> | | |-- key
> >>> | | |-- name ("etc/smbios/smbios-tables")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 34
> >>> | | |-- key
> >>> | | |-- name ("etc/smbios/smbios-anchor")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 35
> >>> | | |-- key
> >>> | | |-- name ("etc/e820")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 36
> >>> | | |-- key
> >>> | | |-- name ("genroms/kvmvapic.bin")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 37
> >>> | | |-- key
> >>> | | |-- name ("etc/system-states")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 38
> >>> | | |-- key
> >>> | | |-- name ("etc/acpi/tables")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 39
> >>> | | |-- key
> >>> | | |-- name ("etc/table-loader")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 40
> >>> | | |-- key
> >>> | | |-- name ("etc/tpm/log")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | |-- 41
> >>> | | |-- key
> >>> | | |-- name ("etc/acpi/rsdp")
> >>> | | |-- raw
> >>> | | `-- size
> >>> | `-- 42
> >>> | |-- key
> >>> | |-- name ("bootorder")
> >>> | |-- raw
> >>> | `-- size
> >>> |
> >>> ...
> >>>
> >>> Patch 3/4 also gets us a "human readable" "by_name" listing, like so:
> >>>
> >>> ...
> >>> |-- by_name
> >>> | |-- bootorder -> ../by_key/42
> >>> | |-- etc
> >>> | | |-- acpi
> >>> | | | |-- rsdp -> ../../../by_key/41
> >>> | | | `-- tables -> ../../../by_key/38
> >>> | | |-- boot-fail-wait -> ../../by_key/32
> >>> | | |-- e820 -> ../../by_key/35
> >>> | | |-- smbios
> >>> | | | |-- smbios-anchor -> ../../../by_key/34
> >>> | | | `-- smbios-tables -> ../../../by_key/33
> >>> | | |-- system-states -> ../../by_key/37
> >>> | | |-- table-loader -> ../../by_key/39
> >>> | | `-- tpm
> >>> | | `-- log -> ../../../by_key/40
> >>> | `-- genroms
> >>> | `-- kvmvapic.bin -> ../../by_key/36
> >>> `-- rev
>
> Gabriel Somlo (4):
> firmware: introduce sysfs driver for QEMU's fw_cfg device
> kobject: export kset_find_obj() for module use
> firmware: create directory hierarchy for sysfs fw_cfg entries
> devicetree: update documentation for fw_cfg ARM bindings
>
> .../ABI/testing/sysfs-firmware-qemu_fw_cfg | 100 +++
> Documentation/devicetree/bindings/arm/fw-cfg.txt | 38 +-
> drivers/firmware/Kconfig | 19 +
> drivers/firmware/Makefile | 1 +
> drivers/firmware/qemu_fw_cfg.c | 735 +++++++++++++++++++++
> lib/kobject.c | 1 +
> 6 files changed, 858 insertions(+), 36 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
> create mode 100644 drivers/firmware/qemu_fw_cfg.c
>
> --
> 2.4.3
>
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