| Message ID | 20220622145052.4012981-1-alex.bennee@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [RFC] qemu-options: bring the kernel and image options together | expand |
On 6/22/22 16:50, Alex Bennée wrote: > How to control the booting of QEMU is often a source of confusion for > users. Bring the options that control this together in the manual > pages and add some verbiage to describe when each option is > appropriate. > > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > Cc: Cédric Le Goater <clg@kaod.org> > --- > qemu-options.hx | 80 ++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 62 insertions(+), 18 deletions(-) > > diff --git a/qemu-options.hx b/qemu-options.hx > index 377d22fbd8..9b0242f0ef 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -1585,13 +1585,6 @@ SRST > Use file as SecureDigital card image. > ERST > > -DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, > - "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) > -SRST > -``-pflash file`` > - Use file as a parallel flash image. > -ERST > -> DEF("snapshot", 0, QEMU_OPTION_snapshot, > "-snapshot write to temporary files instead of disk image files\n", > QEMU_ARCH_ALL) > @@ -3680,12 +3673,51 @@ DEFHEADING() > > #endif > > -DEFHEADING(Linux/Multiboot boot specific:) > +DEFHEADING(Boot Image or Kernel specific:) > +SRST > +There are broadly 4 ways you can boot a system with QEMU. > + > + - specify a firmware and let it control finding a kernel > + - specify a firmware and pass a hint to the kernel to boot > + - direct kernel image boot > + - manually load files into the guests address space > + > +The last method is useful for quickly testing kernels but as there is > +no firmware to pass configuration information to the kernel it must > +either be built for the exact configuration or be handed a DTB blob > +which tells the kernel what drivers it needs. The last method can also load any FW blob with the correct executable layout (reset vector). > + > +ERST > + > +SRST > + > +For x86 machines ``-bios`` will generally do the right thing with > +whatever it is given. For non-x86 machines the more strict ``-pflash`` > +option needs an image that is sized for the flash device for the given > +machine type. Some ppc machine use -bios also, mac, pseries, PowerNV (let's not restrict to x86). LGTM. Thanks, C. > + > +ERST > + > +DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ > + "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) > +SRST > +``-bios file`` > + Set the filename for the BIOS. > +ERST > + > +DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, > + "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) > +SRST > +``-pflash file`` > + Use file as a parallel flash image. > +ERST > + > SRST > -When using these options, you can use a given Linux or Multiboot kernel > -without installing it in the disk image. It can be useful for easier > -testing of various kernels. > > +The kernel options were designed to work with Linux kernels although > +other things (like hypervisors) can be packaged up as a kernel > +executable image. The exact format of a executable image is usually > +architecture specific. > ERST > > @@ -3725,6 +3757,25 @@ SRST > kernel on boot. > ERST > > +SRST > + > +Finally you can also manually load images directly into the address > +space of the guest. This is most useful for developers who already > +know the layout of their guest and take care to ensure something sane > +will happen when the reset vector executes. > + > +The generic loader can be invoked by using the loader device: > + > +``-device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>]`` > + > +there is also the guest loader which operates in a similar way but > +tweaks the DTB so a hypervisor loaded via ``-kernel`` can find where > +the guest image is: > + > +``-device guest-loader,addr=<addr>[,kernel=<path>,[bootargs=<arguments>]][,initrd=<path>]`` > +ERST > + > DEFHEADING() > > DEFHEADING(Debug/Expert options:) > @@ -4175,13 +4226,6 @@ SRST > To list all the data directories, use ``-L help``. > ERST > > -DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ > - "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) > -SRST > -``-bios file`` > - Set the filename for the BIOS. > -ERST > - > DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ > "-enable-kvm enable KVM full virtualization support\n", > QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC |
Cédric Le Goater <clg@kaod.org> writes: > On 6/22/22 16:50, Alex Bennée wrote: >> How to control the booting of QEMU is often a source of confusion for >> users. Bring the options that control this together in the manual >> pages and add some verbiage to describe when each option is >> appropriate. >> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> >> Cc: Cédric Le Goater <clg@kaod.org> >> --- >> qemu-options.hx | 80 ++++++++++++++++++++++++++++++++++++++----------- >> 1 file changed, 62 insertions(+), 18 deletions(-) >> diff --git a/qemu-options.hx b/qemu-options.hx >> index 377d22fbd8..9b0242f0ef 100644 >> --- a/qemu-options.hx >> +++ b/qemu-options.hx >> @@ -1585,13 +1585,6 @@ SRST >> Use file as SecureDigital card image. >> ERST >> -DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, >> - "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) >> -SRST >> -``-pflash file`` >> - Use file as a parallel flash image. >> -ERST >> -> DEF("snapshot", 0, QEMU_OPTION_snapshot, >> "-snapshot write to temporary files instead of disk image files\n", >> QEMU_ARCH_ALL) >> @@ -3680,12 +3673,51 @@ DEFHEADING() >> #endif >> -DEFHEADING(Linux/Multiboot boot specific:) >> +DEFHEADING(Boot Image or Kernel specific:) >> +SRST >> +There are broadly 4 ways you can boot a system with QEMU. >> + >> + - specify a firmware and let it control finding a kernel >> + - specify a firmware and pass a hint to the kernel to boot >> + - direct kernel image boot >> + - manually load files into the guests address space >> + >> +The last method is useful for quickly testing kernels but as there is >> +no firmware to pass configuration information to the kernel it must >> +either be built for the exact configuration or be handed a DTB blob >> +which tells the kernel what drivers it needs. > > The last method can also load any FW blob with the correct executable > layout (reset vector). Heh - actually I wrote that paragraph for the direct kernel image boot and then added the manual option after the fact. I'll try and clean that up to make it clearer. > >> + >> +ERST >> + >> +SRST >> + >> +For x86 machines ``-bios`` will generally do the right thing with >> +whatever it is given. For non-x86 machines the more strict ``-pflash`` >> +option needs an image that is sized for the flash device for the given >> +machine type. > > Some ppc machine use -bios also, mac, pseries, PowerNV (let's not restrict > to x86). Ahh the magic some ;-) Does it essentially rely on if the correct plumbing has been done for the machine? Anything I can look for to audit other machine types? > > > LGTM. > > Thanks, > > C. > > >> + >> +ERST >> + >> +DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ >> + "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) >> +SRST >> +``-bios file`` >> + Set the filename for the BIOS. >> +ERST >> + >> +DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, >> + "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) >> +SRST >> +``-pflash file`` >> + Use file as a parallel flash image. >> +ERST >> + >> SRST >> -When using these options, you can use a given Linux or Multiboot kernel >> -without installing it in the disk image. It can be useful for easier >> -testing of various kernels. >> +The kernel options were designed to work with Linux kernels >> although >> +other things (like hypervisors) can be packaged up as a kernel >> +executable image. The exact format of a executable image is usually >> +architecture specific. >> ERST >> @@ -3725,6 +3757,25 @@ SRST >> kernel on boot. >> ERST >> +SRST >> + >> +Finally you can also manually load images directly into the address >> +space of the guest. This is most useful for developers who already >> +know the layout of their guest and take care to ensure something sane >> +will happen when the reset vector executes. >> + >> +The generic loader can be invoked by using the loader device: >> + >> +``-device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>]`` >> + >> +there is also the guest loader which operates in a similar way but >> +tweaks the DTB so a hypervisor loaded via ``-kernel`` can find where >> +the guest image is: >> + >> +``-device guest-loader,addr=<addr>[,kernel=<path>,[bootargs=<arguments>]][,initrd=<path>]`` >> +ERST >> + >> DEFHEADING() >> DEFHEADING(Debug/Expert options:) >> @@ -4175,13 +4226,6 @@ SRST >> To list all the data directories, use ``-L help``. >> ERST >> -DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ >> - "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) >> -SRST >> -``-bios file`` >> - Set the filename for the BIOS. >> -ERST >> - >> DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ >> "-enable-kvm enable KVM full virtualization support\n", >> QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC |
On Wed, 22 Jun 2022 at 15:53, Alex Bennée <alex.bennee@linaro.org> wrote: > > How to control the booting of QEMU is often a source of confusion for > users. Bring the options that control this together in the manual > pages and add some verbiage to describe when each option is > appropriate. https://stackoverflow.com/a/58434837/4499941 is my answer to this common user question, though it's a bit more conversational in tone than we want for the manual :-) > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > Cc: Cédric Le Goater <clg@kaod.org> > --- > qemu-options.hx | 80 ++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 62 insertions(+), 18 deletions(-) > > diff --git a/qemu-options.hx b/qemu-options.hx > index 377d22fbd8..9b0242f0ef 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -1585,13 +1585,6 @@ SRST > Use file as SecureDigital card image. > ERST > > -DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, > - "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) > -SRST > -``-pflash file`` > - Use file as a parallel flash image. > -ERST > - > DEF("snapshot", 0, QEMU_OPTION_snapshot, > "-snapshot write to temporary files instead of disk image files\n", > QEMU_ARCH_ALL) > @@ -3680,12 +3673,51 @@ DEFHEADING() > > #endif > > -DEFHEADING(Linux/Multiboot boot specific:) > +DEFHEADING(Boot Image or Kernel specific:) > +SRST > +There are broadly 4 ways you can boot a system with QEMU. > + > + - specify a firmware and let it control finding a kernel > + - specify a firmware and pass a hint to the kernel to boot > + - direct kernel image boot > + - manually load files into the guests address space "guest's" > + > +The last method Do you mean the third method? The last method isn't usually used to load kernels, but rather bare-metal binaries. is useful for quickly testing kernels but as there is > +no firmware to pass configuration information to the kernel it must > +either be built for the exact configuration or be handed a DTB blob > +which tells the kernel what drivers it needs. This is all somewhat architecture specific: you don't necessarily need to do either of those if the hardware is probeable. You should also mention that all of this is board specific. > + > +ERST > + > +SRST > + > +For x86 machines ``-bios`` will generally do the right thing with > +whatever it is given. For non-x86 machines the more strict ``-pflash`` > +option needs an image that is sized for the flash device for the given > +machine type. -bios works for some non-x86 machine types too. Ideally we would: * have all our machine types have some documentation * have the documentation for each machine type say whether it supports -bios or not, and what it does > + > +ERST > + > +DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ > + "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) > +SRST > +``-bios file`` > + Set the filename for the BIOS. > +ERST > + > +DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, > + "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) > +SRST > +``-pflash file`` > + Use file as a parallel flash image. > +ERST > + > SRST > -When using these options, you can use a given Linux or Multiboot kernel > -without installing it in the disk image. It can be useful for easier > -testing of various kernels. > > +The kernel options were designed to work with Linux kernels although > +other things (like hypervisors) can be packaged up as a kernel > +executable image. The exact format of a executable image is usually > +architecture specific. > > ERST > > @@ -3725,6 +3757,25 @@ SRST > kernel on boot. > ERST > > +SRST > + > +Finally you can also manually load images directly into the address > +space of the guest. This is most useful for developers who already > +know the layout of their guest and take care to ensure something sane > +will happen when the reset vector executes. We should say that this is the favoured option for "I want to run a bare-metal binary", and we should also say that this option works the same way on any architecture and machine. > + > +The generic loader can be invoked by using the loader device: > + > +``-device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>]`` > + > +there is also the guest loader which operates in a similar way but > +tweaks the DTB so a hypervisor loaded via ``-kernel`` can find where > +the guest image is: > + > +``-device guest-loader,addr=<addr>[,kernel=<path>,[bootargs=<arguments>]][,initrd=<path>]`` > + > +ERST > + > DEFHEADING() thanks -- PMM
On 6/23/22 12:21, Alex Bennée wrote: > > Cédric Le Goater <clg@kaod.org> writes: > >> On 6/22/22 16:50, Alex Bennée wrote: >>> How to control the booting of QEMU is often a source of confusion for >>> users. Bring the options that control this together in the manual >>> pages and add some verbiage to describe when each option is >>> appropriate. >>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> >>> Cc: Cédric Le Goater <clg@kaod.org> >>> --- >>> qemu-options.hx | 80 ++++++++++++++++++++++++++++++++++++++----------- >>> 1 file changed, 62 insertions(+), 18 deletions(-) >>> diff --git a/qemu-options.hx b/qemu-options.hx >>> index 377d22fbd8..9b0242f0ef 100644 >>> --- a/qemu-options.hx >>> +++ b/qemu-options.hx >>> @@ -1585,13 +1585,6 @@ SRST >>> Use file as SecureDigital card image. >>> ERST >>> -DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, >>> - "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) >>> -SRST >>> -``-pflash file`` >>> - Use file as a parallel flash image. >>> -ERST >>> -> DEF("snapshot", 0, QEMU_OPTION_snapshot, >>> "-snapshot write to temporary files instead of disk image files\n", >>> QEMU_ARCH_ALL) >>> @@ -3680,12 +3673,51 @@ DEFHEADING() >>> #endif >>> -DEFHEADING(Linux/Multiboot boot specific:) >>> +DEFHEADING(Boot Image or Kernel specific:) >>> +SRST >>> +There are broadly 4 ways you can boot a system with QEMU. >>> + >>> + - specify a firmware and let it control finding a kernel >>> + - specify a firmware and pass a hint to the kernel to boot >>> + - direct kernel image boot >>> + - manually load files into the guests address space >>> + >>> +The last method is useful for quickly testing kernels but as there is >>> +no firmware to pass configuration information to the kernel it must >>> +either be built for the exact configuration or be handed a DTB blob >>> +which tells the kernel what drivers it needs. >> >> The last method can also load any FW blob with the correct executable >> layout (reset vector). > > Heh - actually I wrote that paragraph for the direct kernel image boot > and then added the manual option after the fact. I'll try and clean that > up to make it clearer. > >> >>> + >>> +ERST >>> + >>> +SRST >>> + >>> +For x86 machines ``-bios`` will generally do the right thing with >>> +whatever it is given. For non-x86 machines the more strict ``-pflash`` >>> +option needs an image that is sized for the flash device for the given >>> +machine type. >> >> Some ppc machine use -bios also, mac, pseries, PowerNV (let's not restrict >> to x86). > > Ahh the magic some ;-) Does it essentially rely on if the correct > plumbing has been done for the machine? They rely on finding a reset vector. So yes, the FW should be mapped where it is expected and have vectors. The machines also know how to expose kernel/initrd to the FW and the FWs have runtime services. It's more than a kernel loader. > Anything I can look for to audit other machine types? Good question. There are some many ways to start a machine. The avocado tests should be a good reference and here is a little tool I use to verify that the PPC machines supported in QEMU boot correctly : https://github.com/legoater/qemu-ppc-boot/blob/main/ppc-boot.sh Sometime ago, I did a model for a MicroWatt SoC, a POWER9 FPGA implementation, and I found quite a few ways to boot from some blob. See : https://github.com/qemu/qemu/commit/2f43989f87332c226358c1f3ef7b96d94ba342ca I guess when FW runtime services are required so is -bios. Else all these options : -kernel -bios -device loader -drive <flash> can be used more or less in the same way. Thanks, C. > >> >> >> LGTM. >> >> Thanks, >> >> C. >> >> >>> + >>> +ERST >>> + >>> +DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ >>> + "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) >>> +SRST >>> +``-bios file`` >>> + Set the filename for the BIOS. >>> +ERST >>> + >>> +DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, >>> + "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) >>> +SRST >>> +``-pflash file`` >>> + Use file as a parallel flash image. >>> +ERST >>> + >>> SRST >>> -When using these options, you can use a given Linux or Multiboot kernel >>> -without installing it in the disk image. It can be useful for easier >>> -testing of various kernels. >>> +The kernel options were designed to work with Linux kernels >>> although >>> +other things (like hypervisors) can be packaged up as a kernel >>> +executable image. The exact format of a executable image is usually >>> +architecture specific. >>> ERST >>> @@ -3725,6 +3757,25 @@ SRST >>> kernel on boot. >>> ERST >>> +SRST >>> + >>> +Finally you can also manually load images directly into the address >>> +space of the guest. This is most useful for developers who already >>> +know the layout of their guest and take care to ensure something sane >>> +will happen when the reset vector executes. >>> + >>> +The generic loader can be invoked by using the loader device: >>> + >>> +``-device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>]`` >>> + >>> +there is also the guest loader which operates in a similar way but >>> +tweaks the DTB so a hypervisor loaded via ``-kernel`` can find where >>> +the guest image is: >>> + >>> +``-device guest-loader,addr=<addr>[,kernel=<path>,[bootargs=<arguments>]][,initrd=<path>]`` >>> +ERST >>> + >>> DEFHEADING() >>> DEFHEADING(Debug/Expert options:) >>> @@ -4175,13 +4226,6 @@ SRST >>> To list all the data directories, use ``-L help``. >>> ERST >>> -DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ >>> - "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) >>> -SRST >>> -``-bios file`` >>> - Set the filename for the BIOS. >>> -ERST >>> - >>> DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ >>> "-enable-kvm enable KVM full virtualization support\n", >>> QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC | > >
diff --git a/qemu-options.hx b/qemu-options.hx index 377d22fbd8..9b0242f0ef 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -1585,13 +1585,6 @@ SRST Use file as SecureDigital card image. ERST -DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, - "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) -SRST -``-pflash file`` - Use file as a parallel flash image. -ERST - DEF("snapshot", 0, QEMU_OPTION_snapshot, "-snapshot write to temporary files instead of disk image files\n", QEMU_ARCH_ALL) @@ -3680,12 +3673,51 @@ DEFHEADING() #endif -DEFHEADING(Linux/Multiboot boot specific:) +DEFHEADING(Boot Image or Kernel specific:) +SRST +There are broadly 4 ways you can boot a system with QEMU. + + - specify a firmware and let it control finding a kernel + - specify a firmware and pass a hint to the kernel to boot + - direct kernel image boot + - manually load files into the guests address space + +The last method is useful for quickly testing kernels but as there is +no firmware to pass configuration information to the kernel it must +either be built for the exact configuration or be handed a DTB blob +which tells the kernel what drivers it needs. + +ERST + +SRST + +For x86 machines ``-bios`` will generally do the right thing with +whatever it is given. For non-x86 machines the more strict ``-pflash`` +option needs an image that is sized for the flash device for the given +machine type. + +ERST + +DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ + "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) +SRST +``-bios file`` + Set the filename for the BIOS. +ERST + +DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, + "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) +SRST +``-pflash file`` + Use file as a parallel flash image. +ERST + SRST -When using these options, you can use a given Linux or Multiboot kernel -without installing it in the disk image. It can be useful for easier -testing of various kernels. +The kernel options were designed to work with Linux kernels although +other things (like hypervisors) can be packaged up as a kernel +executable image. The exact format of a executable image is usually +architecture specific. ERST @@ -3725,6 +3757,25 @@ SRST kernel on boot. ERST +SRST + +Finally you can also manually load images directly into the address +space of the guest. This is most useful for developers who already +know the layout of their guest and take care to ensure something sane +will happen when the reset vector executes. + +The generic loader can be invoked by using the loader device: + +``-device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>]`` + +there is also the guest loader which operates in a similar way but +tweaks the DTB so a hypervisor loaded via ``-kernel`` can find where +the guest image is: + +``-device guest-loader,addr=<addr>[,kernel=<path>,[bootargs=<arguments>]][,initrd=<path>]`` + +ERST + DEFHEADING() DEFHEADING(Debug/Expert options:) @@ -4175,13 +4226,6 @@ SRST To list all the data directories, use ``-L help``. ERST -DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ - "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) -SRST -``-bios file`` - Set the filename for the BIOS. -ERST - DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ "-enable-kvm enable KVM full virtualization support\n", QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC |
How to control the booting of QEMU is often a source of confusion for users. Bring the options that control this together in the manual pages and add some verbiage to describe when each option is appropriate. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Cc: Cédric Le Goater <clg@kaod.org> --- qemu-options.hx | 80 ++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 62 insertions(+), 18 deletions(-)