Date: Wed, 17 Jun 2020 13:11:28 -0700 (PDT) From: "Rodney W. Grimes" <freebsd-rwg@gndrsh.dnsmgr.net> To: Rebecca Cran <rebecca@bsdio.com> Cc: Warner Losh <imp@bsdimp.com>, "Rodney W. Grimes" <freebsd-rwg@gndrsh.dnsmgr.net>, Miguel C <miguelmclara@gmail.com>, FreeBSD Current <FreeBSD-current@freebsd.org> Subject: Re: CTF: UEFI HTTP boot support Message-ID: <202006172011.05HKBS4q087132@gndrsh.dnsmgr.net> In-Reply-To: <890A1C97-31A1-46F9-BE9B-340F6039DD45@bsdio.com>
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> > > On Jun 17, 2020, at 12:12 PM, Warner Losh <imp@bsdimp.com> wrote: > > > > I missed the start of this thread, so maybe I'm missing a key detail. However, I thought UEFI didn't have a RAM-disk, per se, but that we could load memory areas and pass that into the kernel using freebsd-only methods. But UEFI is a bit weird, so maybe it will generate a virtual cdrom... > > See https://uefi.org/sites/default/files/resources/FINAL%20Pres4%20UEFI%20HTTP%20Boot.pdf > > ? RAM Disk Standard > > ? UEFI 2.5 defined RAM Disk device path nodes > - Standard access to a RAM Disk in UEFI > - Supports Virtual Disk and Virtual CD (ISO image) in persistent or > volatile memory? Does freeBSD have any way to access these "Virtual Disk" or Virtual CD images once we leave the world of the loader? I believe we do not, as these are BIOS/UEFI devices that require calls into the UEFI code, which, IIRC is gone once we exit the loader and start the kernel proper, or shortly there after. As far as I know these devices well not be found by the FreeBSD cam layer ATA or AHCI drivers as they do not present an actual PCI device to find. > Rebecca Cran -- Rod Grimes rgrimes@freebsd.org
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