Re: [PATCH v3 6/6] hw/i386/pc_sysfw: Alias rather than copy isa-bios region

[Bernhard Beschow <shentey@gmail.com>]

Am 8. Mai 2024 17:55:07 UTC schrieb Bernhard Beschow <shentey@gmail.com>:
>In the -bios case the "isa-bios" memory region is an alias to the BIOS mapped
>to the top of the 4G memory boundary. Do the same in the -pflash case, but only
>for new machine versions for migration compatibility. This establishes common
>behavior and makes pflash commands work in the "isa-bios" region which some
>real-world legacy bioses rely on.
>
>Note that in the sev_enabled() case, the "isa-bios" memory region in the -pflash
>case will now also point to encrypted memory, just like it already does in the
>-bios case.
>
>When running `info mtree` before and after this commit with
>`qemu-system-x86_64 -S -drive \
>if=pflash,format=raw,readonly=on,file=/usr/share/qemu/bios-256k.bin` and running
>`diff -u before.mtree after.mtree` results in the following changes in the
>memory tree:
>
>   --- before.mtree
>   +++ after.mtree
>   @@ -71,7 +71,7 @@
>        0000000000000000-ffffffffffffffff (prio -1, i/o): pci
>        00000000000a0000-00000000000bffff (prio 1, i/o): vga-lowmem
>        00000000000c0000-00000000000dffff (prio 1, rom): pc.rom
>   -      00000000000e0000-00000000000fffff (prio 1, rom): isa-bios
>   +      00000000000e0000-00000000000fffff (prio 1, romd): alias isa-bios @system.flash0 0000000000020000-000000000003ffff
>        00000000000a0000-00000000000bffff (prio 1, i/o): alias smram-region @pci 00000000000a0000-00000000000bffff
>        00000000000c0000-00000000000c3fff (prio 1, i/o): alias pam-pci @pci 00000000000c0000-00000000000c3fff
>        00000000000c4000-00000000000c7fff (prio 1, i/o): alias pam-pci @pci 00000000000c4000-00000000000c7fff
>   @@ -108,7 +108,7 @@
>        0000000000000000-ffffffffffffffff (prio -1, i/o): pci
>        00000000000a0000-00000000000bffff (prio 1, i/o): vga-lowmem
>        00000000000c0000-00000000000dffff (prio 1, rom): pc.rom
>   -      00000000000e0000-00000000000fffff (prio 1, rom): isa-bios
>   +      00000000000e0000-00000000000fffff (prio 1, romd): alias isa-bios @system.flash0 0000000000020000-000000000003ffff
>        00000000000a0000-00000000000bffff (prio 1, i/o): alias smram-region @pci 00000000000a0000-00000000000bffff
>        00000000000c0000-00000000000c3fff (prio 1, i/o): alias pam-pci @pci 00000000000c0000-00000000000c3fff
>        00000000000c4000-00000000000c7fff (prio 1, i/o): alias pam-pci @pci 00000000000c4000-00000000000c7fff
>   @@ -131,11 +131,14 @@
>   memory-region: pc.ram
>   0000000000000000-0000000007ffffff (prio 0, ram): pc.ram
>
>   +memory-region: system.flash0
>   +  00000000fffc0000-00000000ffffffff (prio 0, romd): system.flash0
>   +
>   memory-region: pci
>   0000000000000000-ffffffffffffffff (prio -1, i/o): pci
>        00000000000a0000-00000000000bffff (prio 1, i/o): vga-lowmem
>        00000000000c0000-00000000000dffff (prio 1, rom): pc.rom
>   -    00000000000e0000-00000000000fffff (prio 1, rom): isa-bios
>   +    00000000000e0000-00000000000fffff (prio 1, romd): alias isa-bios @system.flash0 0000000000020000-000000000003ffff
>
>   memory-region: smram
>        00000000000a0000-00000000000bffff (prio 0, ram): alias smram-low @pc.ram 00000000000a0000-00000000000bffff
>
>Note that in both cases the "system" memory region contains the entry
>
>  00000000fffc0000-00000000ffffffff (prio 0, romd): system.flash0
>
>but the "system.flash0" memory region only appears standalone when "isa-bios" is
>an alias.
>
>Signed-off-by: Bernhard Beschow <shentey@gmail.com>

Ping

This is the only patch in this series which hasn't got an R-b tag yet (the others are already in master) and I'm not aware of any open issues.

Best regards,
Bernhard