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| author | Zeng Chi <zengchi@kylinos.cn> | 2026-09-21 18:24:42 +0800 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2026-09-22 08:36:16 -0700 |
| commit | 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d (patch) | |
| tree | 660d50d4139cb750fbde1ae3432452c20726c99d /Documentation/fb/efifb.rst | |
| download | linux-stable-119e9db233ad0f4cbd4cfb9f9385a7bca378b37d.tar.gz linux-stable-119e9db233ad0f4cbd4cfb9f9385a7bca378b37d.zip | |
KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted
Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.
Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'Documentation/fb/efifb.rst')
| -rw-r--r-- | Documentation/fb/efifb.rst | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/Documentation/fb/efifb.rst b/Documentation/fb/efifb.rst new file mode 100644 index 000000000..3d4aab406 --- /dev/null +++ b/Documentation/fb/efifb.rst @@ -0,0 +1,71 @@ +=================================== +efifb - Generic EFI platform driver +=================================== + +This is a generic EFI platform driver for systems with UEFI firmware. The +system must be booted via the EFI stub for this to be usable. efifb supports +both firmware with Graphics Output Protocol (GOP) displays as well as older +systems with only Universal Graphics Adapter (UGA) displays. + +Supported Hardware +================== + +- iMac 17"/20" +- Macbook +- Macbook Pro 15"/17" +- MacMini +- ARM/ARM64/X86 systems with UEFI firmware + +How to use it? +============== + +For UGA displays, efifb does not have any kind of autodetection of your +machine. + +You have to add the following kernel parameters in your elilo.conf:: + + Macbook : + video=efifb:macbook + MacMini : + video=efifb:mini + Macbook Pro 15", iMac 17" : + video=efifb:i17 + Macbook Pro 17", iMac 20" : + video=efifb:i20 + +For GOP displays, efifb can autodetect the display's resolution and framebuffer +address, so these should work out of the box without any special parameters. + +Accepted options: + +======= =========================================================== +nowc Don't map the framebuffer write combined. This can be used + to workaround side-effects and slowdowns on other CPU cores + when large amounts of console data are written. +======= =========================================================== + +Options for GOP displays: + +mode=n + The EFI stub will set the mode of the display to mode number n if + possible. + +<xres>x<yres>[-(rgb|bgr|<bpp>)] + The EFI stub will search for a display mode that matches the specified + horizontal and vertical resolution, and optionally bit depth, and set + the mode of the display to it if one is found. The bit depth can either + "rgb" or "bgr" to match specifically those pixel formats, or a number + for a mode with matching bits per pixel. + +auto + The EFI stub will choose the mode with the highest resolution (product + of horizontal and vertical resolution). If there are multiple modes + with the highest resolution, it will choose one with the highest color + depth. + +list + The EFI stub will list out all the display modes that are available. A + specific mode can then be chosen using one of the above options for the + next boot. + +Edgar Hucek <gimli@dark-green.com> |