Hi Andre, On 3/3/21 2:18 PM, Andre Przywara wrote: > On Fri, 19 Feb 2021 16:37:18 +0000 > Alexandru Elisei <alexandru.elisei@xxxxxxx> wrote: > >> Currently, the UART early address is set indirectly with the --vmm option >> and there are only two possible values: if the VMM is qemu (the default), >> then the UART address is set to 0x09000000; if the VMM is kvmtool, then the >> UART address is set to 0x3f8. >> >> There several efforts under way to change the kvmtool UART address, and >> kvm-unit-tests so far hasn't had mechanism to let the user set a specific >> address, which means that the early UART won't be available. >> >> This situation will only become worse as kvm-unit-tests gains support to >> run as an EFI app, as each platform will have their own UART type and >> address. >> >> To address both issues, a new configure option is added, --earlycon. The >> syntax and semantics are identical to the kernel parameter with the same >> name. > Nice one! I like that reusing of an existing scheme. > >> Specifying this option will overwrite the UART address set by --vmm. >> >> At the moment, the UART type and register width parameters are ignored >> since both qemu's and kvmtool's UART emulation use the same offset for the >> TX register and no other registers are used by kvm-unit-tests, but the >> parameters will become relevant once EFI support is added. >> >> Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx> >> --- >> The kvmtool patches I was referring to are the patches to unify ioport and >> MMIO emulation [1] and to allow the user to specify a custom memory layout >> for the VM [2] (these patches are very old, but I plan to revive them after >> the ioport and MMIO unification series are merged). >> >> [1] https://lore.kernel.org/kvm/20201210142908.169597-1-andre.przywara@xxxxxxx/T/#t >> [2] https://lore.kernel.org/kvm/1569245722-23375-1-git-send-email-alexandru.elisei@xxxxxxx/ >> >> configure | 35 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 35 insertions(+) >> >> diff --git a/configure b/configure >> index cdcd34e94030..d94b92255088 100755 >> --- a/configure >> +++ b/configure >> @@ -26,6 +26,7 @@ errata_force=0 >> erratatxt="$srcdir/errata.txt" >> host_key_document= >> page_size= >> +earlycon= >> >> usage() { >> cat <<-EOF >> @@ -54,6 +55,17 @@ usage() { >> --page-size=PAGE_SIZE >> Specify the page size (translation granule) (4k, 16k or >> 64k, default is 64k, arm64 only) >> + --earlycon=EARLYCON >> + Specify the UART name, type and address (optional, arm and >> + arm64 only). The specified address will overwrite the UART >> + address set by the --vmm option. EARLYCON can be on of (case >> + sensitive): >> + uart[8250],mmio,ADDR >> + Specify an 8250 compatible UART at address ADDR. Supported >> + register stride is 8 bit only. >> + pl011,mmio,ADDR >> + Specify a PL011 compatible UART at address ADDR. Supported >> + register stride is 8 bit only. > I think the PL011 only ever specified 32-bit register accesses? I just You are correct, according to Arm Base System Architecture 1.0 (DEN0094A), page 43: "The registers that are described in this specification are a subset of the Arm PL011 r1p5 UART. [..] The Generic UART is specified as a set of 32-bit registers. [..] The Generic UART is little-endian." > see that we actually do a writeb() for puts, that is not guaranteed to > work on a hardware PL011, AFAIK. I guess QEMU just doesn't care ... Table 19, page 43 of DEN0094A, says that permitted accesses sizes for the UARTDR register are 8, 16 and 32 bits. I think using writeb() at address 0 of the UART memory region to write a character is correct. > Looks like we should fix this, maybe we get mmio32 for uart8250 for > free, then. > > The kernel specifies "pl011,mmio32,ADDR" or "pl011,ADDR", so I think we > should keep it compatible. "mmio[32]" is pretty much redundant on the > PL011 (no port I/O), I think it's just for consistency with the 8250. > Can you tweak the routine below to make this optional, and also accept > mmio32? Definitely, my intention was to make it as close as possible to what Linux does. I made a mistake when I allowed this value, I will change it in the next version. Thanks, Alex > > Cheers, > Andre > >> EOF >> exit 1 >> } >> @@ -112,6 +124,9 @@ while [[ "$1" = -* ]]; do >> --page-size) >> page_size="$arg" >> ;; >> + --earlycon) >> + earlycon="$arg" >> + ;; >> --help) >> usage >> ;; >> @@ -170,6 +185,26 @@ elif [ "$arch" = "arm" ] || [ "$arch" = "arm64" ]; then >> echo '--vmm must be one of "qemu" or "kvmtool"!' >> usage >> fi >> + >> + if [ "$earlycon" ]; then >> + name=$(echo $earlycon|cut -d',' -f1) >> + if [ "$name" != "uart" ] && [ "$name" != "uart8250" ] && >> + [ "$name" != "pl011" ]; then >> + echo "unknown earlycon name: $name" >> + usage >> + fi >> + type=$(echo $earlycon|cut -d',' -f2) >> + if [ "$type" != "mmio" ]; then >> + echo "unknown earlycon type: $type" >> + usage >> + fi >> + addr=$(echo $earlycon|cut -d',' -f3) >> + if [ -z "$addr" ]; then >> + echo "missing earlycon address" >> + usage >> + fi >> + arm_uart_early_addr=$addr >> + fi >> elif [ "$arch" = "ppc64" ]; then >> testdir=powerpc >> firmware="$testdir/boot_rom.bin"
