When the commit 69c1f396f25b ("efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation") moved x86 specific EFI earlyprintk implementation to shared location it also tweaked the behaviour. In particular it dropped a trick with full framebuffer remapping after page initialization. This lead to two regressions: 1) very slow scrolling after page initialization; 2) kernel hang when keep_bootcon parameter is being provided. Returning the trick back fixes #2 and mitigates, i.e. reduces the window when slowness appears, #1 presumably due to eliminating heavy map()/unmap() operations per each pixel line on the screen. Fixes: 69c1f396f25b ("efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation") Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Cc: Alexander Graf <agraf@xxxxxxx> Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> --- v3: - assign size in efi_earlycon_setup() - check base and size before mapping in early_efi_map_fb() drivers/firmware/efi/earlycon.c | 37 +++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c index c9a0efca17b0..60b5350c6105 100644 --- a/drivers/firmware/efi/earlycon.c +++ b/drivers/firmware/efi/earlycon.c @@ -16,15 +16,50 @@ static const struct font_desc *font; static u32 efi_x, efi_y; static u64 fb_base; +static u32 fb_size; static pgprot_t fb_prot; +static void *efi_fb; + +/* + * efi earlycon needs to use early_memremap() to map the framebuffer. + * But early_memremap() is not usable for 'earlycon=efifb keep_bootcon', + * memremap() should be used instead. memremap() will be available after + * paging_init() which is earlier than initcall callbacks. Thus adding this + * early initcall function early_efi_map_fb() to map the whole efi framebuffer. + */ +static int __init early_efi_map_fb(void) +{ + if (!fb_base || !fb_size) + return NULL; + + if (pgprot_val(fb_prot) == pgprot_val(PAGE_KERNEL)) + efi_fb = memremap(fb_base, fb_size, MEMREMAP_WB); + else + efi_fb = memremap(fb_base, fb_size, MEMREMAP_WC); + + return efi_fb ? 0 : -ENOMEM; +} +early_initcall(early_efi_map_fb); + +static void __exit early_efi_unmap_fb(void) +{ + memunmap(efi_fb); +} +__exitcall(early_efi_unmap_fb); static __ref void *efi_earlycon_map(unsigned long start, unsigned long len) { + if (efi_fb) + return efi_fb + start; + return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot)); } static __ref void efi_earlycon_unmap(void *addr, unsigned long len) { + if (efi_fb) + return; + early_memunmap(addr, len); } @@ -176,6 +211,8 @@ static int __init efi_earlycon_setup(struct earlycon_device *device, if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE) fb_base |= (u64)screen_info.ext_lfb_base << 32; + fb_size = screen_info.lfb_size; + if (opt && !strcmp(opt, "ram")) fb_prot = PAGE_KERNEL; else -- 2.24.0