| Message ID | 20250312085424.1201148-6-sughosh.ganu@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Add pmem node for preserving distro ISO's | expand |
On 12.03.25 09:54, Sughosh Ganu wrote: > From: Ilias Apalodimas <ilias.apalodimas@linaro.org> > > One of the problems OS installers face, when running in EFI, is that > the mounted ISO after calling ExitBootServices goes away. For some > distros this is a problem since they rely on finding some core packages > before continuing the installation. Distros have works around this -- > e.g Fedora has a special kernel command line parameter called > inst.stage2 [0]. The patch is about RAM disks and not about installers. > > ACPI has NFIT and NVDIMM support to provide ramdisks to the OS, but we > don't have anything in place for DTs. Linux and device trees have support > for persistent memory devices. > > It's worth noting that for linux to instantiate the /dev/pmemX device, > the memory described in the pmem node has to be omitted from the EFI > memory map we hand over to the OS if ZONE_DEVICES and SPARSEMEM is > enabled. With those enabled the pmem driver ends up calling > devm_memremap_pages() instead of devm_memremap(). The latter works > whether the memory is omitted or marked as reserved, but mapping pages > only works if the memory is omitted. > > On top of that, depending on how the kernel is configured, that memory > area must be page aligned or 2MB aligned. PowerPC is an exception here > and requires 16MB alignment, but since we don't have EFI support for > it, limit the alignment to 2MB. > > Ensure that the ISO image is 2MB aligned and remove the region > occupied by the image from the EFI memory map. > > Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> > Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org> > --- > Changes since V7: None > > lib/efi_loader/efi_bootmgr.c | 22 +++++++++++++++++----- > 1 file changed, 17 insertions(+), 5 deletions(-) > > diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c > index c6124c590d9..081eff057f4 100644 > --- a/lib/efi_loader/efi_bootmgr.c > +++ b/lib/efi_loader/efi_bootmgr.c > @@ -18,6 +18,8 @@ > #include <efi_loader.h> > #include <efi_variable.h> > #include <asm/unaligned.h> > +#include <linux/kernel.h> > +#include <linux/sizes.h> > > static const struct efi_boot_services *bs; > static const struct efi_runtime_services *rs; > @@ -362,13 +364,16 @@ static efi_status_t prepare_loaded_image(u16 *label, ulong addr, ulong size, > } > > /* > - * TODO: expose the ramdisk to OS. > - * Need to pass the ramdisk information by the architecture-specific > - * methods such as 'pmem' device-tree node. > + * Linux supports 'pmem' which allows OS installers to find, reclaim If the RAM disk contains is used by an installer is irrelevant here. If it is a data disk used by an OS the same patch is needed. > + * the mounted images and continue the installation since the contents > + * of the pmem region are treated as local media. > + * > + * The memory regions used for it needs to be carved out of the EFI > + * memory map. > */ > - ret = efi_add_memory_map(addr, size, EFI_RESERVED_MEMORY_TYPE); > + ret = efi_remove_memory_map(addr, size, EFI_CONVENTIONAL_MEMORY); > if (ret != EFI_SUCCESS) { > - log_err("Memory reservation failed\n"); > + log_err("Failed to reserve memory\n"); > goto err; > } > > @@ -490,6 +495,13 @@ static efi_status_t try_load_from_uri_path(struct efi_device_path_uri *uridp, > ret = EFI_INVALID_PARAMETER; > goto err; > } > + /* > + * Depending on the kernel configuration, pmem memory area must be page > + * aligned or 2MB aligned. PowerPC is an exception here and requires %s/pmem memory area/pmem memory areas/ %s/MB/MiB/ Best regards Heinrich > + * 16MB alignment, but since we don't have EFI support for it, limit > + * the alignment to 2MB. > + */ > + image_size = ALIGN(image_size, SZ_2M); > > /* > * If the file extension is ".iso" or ".img", mount it and try to load
On Thu, 13 Mar 2025 at 02:22, Heinrich Schuchardt <heinrich.schuchardt@canonical.com> wrote: > > On 12.03.25 09:54, Sughosh Ganu wrote: > > From: Ilias Apalodimas <ilias.apalodimas@linaro.org> > > > > One of the problems OS installers face, when running in EFI, is that > > the mounted ISO after calling ExitBootServices goes away. For some > > distros this is a problem since they rely on finding some core packages > > before continuing the installation. Distros have works around this -- > > e.g Fedora has a special kernel command line parameter called > > inst.stage2 [0]. > > The patch is about RAM disks and not about installers. Okay, will try to not frame the commit message about installers. > > > > > ACPI has NFIT and NVDIMM support to provide ramdisks to the OS, but we > > don't have anything in place for DTs. Linux and device trees have support > > for persistent memory devices. > > > > It's worth noting that for linux to instantiate the /dev/pmemX device, > > the memory described in the pmem node has to be omitted from the EFI > > memory map we hand over to the OS if ZONE_DEVICES and SPARSEMEM is > > enabled. With those enabled the pmem driver ends up calling > > devm_memremap_pages() instead of devm_memremap(). The latter works > > whether the memory is omitted or marked as reserved, but mapping pages > > only works if the memory is omitted. > > > > On top of that, depending on how the kernel is configured, that memory > > area must be page aligned or 2MB aligned. PowerPC is an exception here > > and requires 16MB alignment, but since we don't have EFI support for > > it, limit the alignment to 2MB. > > > > Ensure that the ISO image is 2MB aligned and remove the region > > occupied by the image from the EFI memory map. > > > > Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> > > Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org> > > --- > > Changes since V7: None > > > > lib/efi_loader/efi_bootmgr.c | 22 +++++++++++++++++----- > > 1 file changed, 17 insertions(+), 5 deletions(-) > > > > diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c > > index c6124c590d9..081eff057f4 100644 > > --- a/lib/efi_loader/efi_bootmgr.c > > +++ b/lib/efi_loader/efi_bootmgr.c > > @@ -18,6 +18,8 @@ > > #include <efi_loader.h> > > #include <efi_variable.h> > > #include <asm/unaligned.h> > > +#include <linux/kernel.h> > > +#include <linux/sizes.h> > > > > static const struct efi_boot_services *bs; > > static const struct efi_runtime_services *rs; > > @@ -362,13 +364,16 @@ static efi_status_t prepare_loaded_image(u16 *label, ulong addr, ulong size, > > } > > > > /* > > - * TODO: expose the ramdisk to OS. > > - * Need to pass the ramdisk information by the architecture-specific > > - * methods such as 'pmem' device-tree node. > > + * Linux supports 'pmem' which allows OS installers to find, reclaim > > If the RAM disk contains is used by an installer is irrelevant here. > If it is a data disk used by an OS the same patch is needed. Will change > > > + * the mounted images and continue the installation since the contents > > + * of the pmem region are treated as local media. > > + * > > + * The memory regions used for it needs to be carved out of the EFI > > + * memory map. > > */ > > - ret = efi_add_memory_map(addr, size, EFI_RESERVED_MEMORY_TYPE); > > + ret = efi_remove_memory_map(addr, size, EFI_CONVENTIONAL_MEMORY); > > if (ret != EFI_SUCCESS) { > > - log_err("Memory reservation failed\n"); > > + log_err("Failed to reserve memory\n"); > > goto err; > > } > > > > @@ -490,6 +495,13 @@ static efi_status_t try_load_from_uri_path(struct efi_device_path_uri *uridp, > > ret = EFI_INVALID_PARAMETER; > > goto err; > > } > > + /* > > + * Depending on the kernel configuration, pmem memory area must be page > > + * aligned or 2MB aligned. PowerPC is an exception here and requires > > %s/pmem memory area/pmem memory areas/ > > %s/MB/MiB/ Will change -sughosh > > Best regards > > Heinrich > > > + * 16MB alignment, but since we don't have EFI support for it, limit > > + * the alignment to 2MB. > > + */ > > + image_size = ALIGN(image_size, SZ_2M); > > > > /* > > * If the file extension is ".iso" or ".img", mount it and try to load >
diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c index c6124c590d9..081eff057f4 100644 --- a/lib/efi_loader/efi_bootmgr.c +++ b/lib/efi_loader/efi_bootmgr.c @@ -18,6 +18,8 @@ #include <efi_loader.h> #include <efi_variable.h> #include <asm/unaligned.h> +#include <linux/kernel.h> +#include <linux/sizes.h> static const struct efi_boot_services *bs; static const struct efi_runtime_services *rs; @@ -362,13 +364,16 @@ static efi_status_t prepare_loaded_image(u16 *label, ulong addr, ulong size, } /* - * TODO: expose the ramdisk to OS. - * Need to pass the ramdisk information by the architecture-specific - * methods such as 'pmem' device-tree node. + * Linux supports 'pmem' which allows OS installers to find, reclaim + * the mounted images and continue the installation since the contents + * of the pmem region are treated as local media. + * + * The memory regions used for it needs to be carved out of the EFI + * memory map. */ - ret = efi_add_memory_map(addr, size, EFI_RESERVED_MEMORY_TYPE); + ret = efi_remove_memory_map(addr, size, EFI_CONVENTIONAL_MEMORY); if (ret != EFI_SUCCESS) { - log_err("Memory reservation failed\n"); + log_err("Failed to reserve memory\n"); goto err; } @@ -490,6 +495,13 @@ static efi_status_t try_load_from_uri_path(struct efi_device_path_uri *uridp, ret = EFI_INVALID_PARAMETER; goto err; } + /* + * Depending on the kernel configuration, pmem memory area must be page + * aligned or 2MB aligned. PowerPC is an exception here and requires + * 16MB alignment, but since we don't have EFI support for it, limit + * the alignment to 2MB. + */ + image_size = ALIGN(image_size, SZ_2M); /* * If the file extension is ".iso" or ".img", mount it and try to load