Revision 31a55cf145f2e3d74a7488e86bd0b33b64250fce authored by Dave Airlie on 19 March 2015, 04:01:42 UTC, committed by Dave Airlie on 19 March 2015, 04:01:42 UTC
Some urgent regression fixes to booting failures Exynos DRM occured.
Summary:
- Fix two urgent null pointer dereference bugs in case of enabling
or disabling IOMMU. There was two cases to these issues.
One is that plane->crtc is accessed by exynos_disable_plane()
when device tree binding is broken so device driver tries
to release, which means that the mode set operation isn't invoked yet
so plane->crtc is still NULL and exynos_disable_plane() will access
NULL pointer. This issue is fixed by checking if the plane->crtc
is NULL or not in exynos_disable_plane()
Other is that fimd_wait_for_vblank() is called to avoid from page fault
with IOMMU before the ctx object is created. At this time,
fimd_wait_for_vblank() tries to access ctx->crtc but the ctx->crtc
is still NULL because exynos_drm_crtc_create() isn't called yet.
This issue is fixed by creating a crtc object and setting it to
ctx->crtc prior to fimd_wait_for_vblank() call.
For more details, you can refer to below an e-mail thread,
http://www.spinics.net/lists/linux-samsung-soc/msg42436.html
- Remove unnecessary file not used and fix trivial issues.
* 'exynos-drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos:
drm/exynos: fix the initialization order in FIMD
drm/exynos: fix typo config name correctly.
drm/exynos: Check for NULL dereference of crtc
drm/exynos: IS_ERR() vs NULL bug
drm/exynos: remove unused files
efi-stub.txt
The EFI Boot Stub
---------------------------
On the x86 and ARM platforms, a kernel zImage/bzImage can masquerade
as a PE/COFF image, thereby convincing EFI firmware loaders to load
it as an EFI executable. The code that modifies the bzImage header,
along with the EFI-specific entry point that the firmware loader
jumps to are collectively known as the "EFI boot stub", and live in
arch/x86/boot/header.S and arch/x86/boot/compressed/eboot.c,
respectively. For ARM the EFI stub is implemented in
arch/arm/boot/compressed/efi-header.S and
arch/arm/boot/compressed/efi-stub.c. EFI stub code that is shared
between architectures is in drivers/firmware/efi/efi-stub-helper.c.
For arm64, there is no compressed kernel support, so the Image itself
masquerades as a PE/COFF image and the EFI stub is linked into the
kernel. The arm64 EFI stub lives in arch/arm64/kernel/efi-entry.S
and arch/arm64/kernel/efi-stub.c.
By using the EFI boot stub it's possible to boot a Linux kernel
without the use of a conventional EFI boot loader, such as grub or
elilo. Since the EFI boot stub performs the jobs of a boot loader, in
a certain sense it *IS* the boot loader.
The EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option.
**** How to install bzImage.efi
The bzImage located in arch/x86/boot/bzImage must be copied to the EFI
System Partition (ESP) and renamed with the extension ".efi". Without
the extension the EFI firmware loader will refuse to execute it. It's
not possible to execute bzImage.efi from the usual Linux file systems
because EFI firmware doesn't have support for them. For ARM the
arch/arm/boot/zImage should be copied to the system partition, and it
may not need to be renamed. Similarly for arm64, arch/arm64/boot/Image
should be copied but not necessarily renamed.
**** Passing kernel parameters from the EFI shell
Arguments to the kernel can be passed after bzImage.efi, e.g.
fs0:> bzImage.efi console=ttyS0 root=/dev/sda4
**** The "initrd=" option
Like most boot loaders, the EFI stub allows the user to specify
multiple initrd files using the "initrd=" option. This is the only EFI
stub-specific command line parameter, everything else is passed to the
kernel when it boots.
The path to the initrd file must be an absolute path from the
beginning of the ESP, relative path names do not work. Also, the path
is an EFI-style path and directory elements must be separated with
backslashes (\). For example, given the following directory layout,
fs0:>
Kernels\
bzImage.efi
initrd-large.img
Ramdisks\
initrd-small.img
initrd-medium.img
to boot with the initrd-large.img file if the current working
directory is fs0:\Kernels, the following command must be used,
fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img
Notice how bzImage.efi can be specified with a relative path. That's
because the image we're executing is interpreted by the EFI shell,
which understands relative paths, whereas the rest of the command line
is passed to bzImage.efi.
**** The "dtb=" option
For the ARM and arm64 architectures, we also need to be able to provide a
device tree to the kernel. This is done with the "dtb=" command line option,
and is processed in the same manner as the "initrd=" option that is
described above.
Computing file changes ...
