From: Arvind Sankar <email@example.com> To: Ard Biesheuvel <firstname.lastname@example.org> Cc: Arvind Sankar <email@example.com>, Ard Biesheuvel <firstname.lastname@example.org>, linux-efi <email@example.com>, Ingo Molnar <firstname.lastname@example.org>, Thomas Gleixner <email@example.com>, Linux Kernel Mailing List <firstname.lastname@example.org>, Andy Shevchenko <email@example.com>, Bhupesh Sharma <firstname.lastname@example.org>, Masayoshi Mizuma <email@example.com> Subject: Re: [PATCH 6/6] efi/earlycon: Remap entire framebuffer after page initialization Date: Tue, 10 Dec 2019 15:05:46 -0500 [thread overview] Message-ID: <20191210200546.GA55356@rani.riverdale.lan> (raw) In-Reply-To: <CAKv+Gu8QWcSwRajsO5voTQJxDHy613ugCd_R6=SStf9ABrmtfQ@mail.gmail.com> On Mon, Dec 09, 2019 at 07:24:13PM +0000, Ard Biesheuvel wrote: > On Mon, 9 Dec 2019 at 20:12, Arvind Sankar <firstname.lastname@example.org> wrote: > > > > On Fri, Dec 06, 2019 at 04:55:42PM +0000, Ard Biesheuvel wrote: > > > From: Andy Shevchenko <email@example.com> > > > > > > When commit 69c1f396f25b > > > > > > "efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation" > > > > > > moved the x86 specific EFI earlyprintk implementation to a shared location, > > > it also tweaked the behaviour. In particular, it dropped a trick with full > > > framebuffer remapping after page initialization, leading to two regressions: > > > 1) very slow scrolling after page initialization, > > > 2) kernel hang when the 'keep_bootcon' command line argument is passed. > > > > > > Putting the tweak back fixes #2 and mitigates #1, i.e., it limits the slow > > > behavior to the early boot stages, presumably due to eliminating heavy > > > map()/unmap() operations per each pixel line on the screen. > > > > > > > Could the efi earlycon have an interaction with PCI resource allocation, > > similar to what commit dcf8f5ce3165 ("drivers/fbdev/efifb: Allow BAR to > > be moved instead of claiming it") fixed for efifb? > > Yes. If the BAR gets moved, things will break. This is mostly an issue > for the keep_bootcon case, but that is documented as being a debug > feature specifically for addressing console initialization related > issues. Earlycon itself is also a debug feature, so if you hit the BAR > reallocation issue, you're simply out of luck. Note that this happens > rarely in practice, only on non-x86 systems where the firmware and the > kernel have very different policies regarding BAR allocation, and on > DT based systems, you can force the OS to honour the existing > allocation by using linux,pci-probe-only Thanks. Another q -- I tried out the earlycon=efifb, and it seems like it gets disabled (without keep_bootcon) as soon as dummycon takes over, which is well before the real console. DUMMY_CONSOLE is defined as depends on VGA_CONSOLE!=y || SGI_NEWPORT_CONSOLE!=y default y so it seems like it will pretty much always be enabled, as it doesn't seem likely that VGA_CONSOLE=y and SGI_NEWPORT_CONSOLE=y would ever be true simultaneously. Am I missing something or is this the way it's supposed to work? So keep_bootcon seems almost necessary with the EFI boot console? Would a patch to not disable boot console when dummycon is initialized, but wait for a real console, be useful? Thanks.
next prev parent reply other threads:[~2019-12-10 20:05 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-06 16:55 [GIT PULL 0/6] EFI fixes for v5.5 Ard Biesheuvel 2019-12-06 16:55 ` [PATCH 1/6] efi/memreserve: register reservations as 'reserved' in /proc/iomem Ard Biesheuvel 2019-12-08 13:33 ` [tip: efi/urgent] efi/memreserve: Register " tip-bot2 for Ard Biesheuvel 2019-12-06 16:55 ` [PATCH 2/6] efi/gop: Return EFI_NOT_FOUND if there are no usable GOPs Ard Biesheuvel 2019-12-08 13:33 ` [tip: efi/urgent] " tip-bot2 for Arvind Sankar 2019-12-06 16:55 ` [PATCH 3/6] efi/gop: Return EFI_SUCCESS if a usable GOP was found Ard Biesheuvel 2019-12-08 13:33 ` [tip: efi/urgent] " tip-bot2 for Arvind Sankar 2019-12-06 16:55 ` [PATCH 4/6] efi/gop: Fix memory leak from __gop_query32/64 Ard Biesheuvel 2019-12-08 13:33 ` [tip: efi/urgent] efi/gop: Fix memory leak in __gop_query32/64() tip-bot2 for Arvind Sankar 2019-12-06 16:55 ` [PATCH 5/6] efi: fix type of unload field in efi_loaded_image_t Ard Biesheuvel 2019-12-08 13:33 ` [tip: efi/urgent] efi: Fix efi_loaded_image_t::unload type tip-bot2 for Arvind Sankar 2019-12-06 16:55 ` [PATCH 6/6] efi/earlycon: Remap entire framebuffer after page initialization Ard Biesheuvel 2019-12-08 13:33 ` [tip: efi/urgent] " tip-bot2 for Andy Shevchenko 2019-12-09 19:12 ` [PATCH 6/6] " Arvind Sankar 2019-12-09 19:24 ` Ard Biesheuvel 2019-12-10 20:05 ` Arvind Sankar [this message] 2019-12-11 11:26 ` Ard Biesheuvel 2019-12-11 15:55 ` Arvind Sankar
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20191210200546.GA55356@rani.riverdale.lan \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --subject='Re: [PATCH 6/6] efi/earlycon: Remap entire framebuffer after page initialization' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.